Eli nqaku liyinxalenye yesihloko sophando esithi “Iiteknoloji zokulungisa izinto eziphilayo eziphambili kunye neenkqubo zokuphinda zisetyenziswe kwiikhompawundi zendalo ezidityanisiweyo (i-SOC). Jonga onke amanqaku ali-14
Ii-polycyclic aromatic hydrocarbons (ii-PAH) ezinobunzima obuphantsi beemolekyuli ezifana ne-naphthalene kunye ne-naphthalenes ezithatyathwe endaweni yazo (i-methylnaphthalene, i-naphthoic acid, i-1-naphthyl-N-methylcarbamate, njl.njl.) zisetyenziswa kakhulu kumashishini ahlukeneyo kwaye zinobuthi be-genotoxic, i-mutagenic kunye/okanye i-carcinogenic kwizinto eziphilayo. Ezi khompawundi ze-organic (ii-SOC) okanye ii-xenobiotics zithathwa njengezingcolisi eziphambili kwaye zibeka umngcipheko omkhulu kwindalo esingqongileyo nakwimpilo yoluntu. Ubunzulu bemisebenzi yabantu (umz. ukufakelwa kwegesi yamalahle, ukucocwa kweoyile, ukukhutshwa kwezithuthi kunye nokusetyenziswa kwezolimo) bumisela uxinaniso, ikamva kunye nokuthuthwa kwezi khompawundi zixhaphakileyo nezihlala zihleli. Ukongeza kwiindlela zonyango/ukususwa ngokwasemzimbeni nangokweekhemikhali, ubuchwepheshe obuluhlaza nobunobuhlobo nokusingqongileyo obufana nokulungiswa kwezinto eziphilayo, ezisebenzisa iintsholongwane ezinokonakalisa ngokupheleleyo ii-POC okanye ukuziguqula zibe yimveliso engeyiyo ityhefu, ziye zavela njengendlela ekhuselekileyo, engabizi kakhulu nethembisayo. Iintlobo ezahlukeneyo zeebhaktiriya ezikwi-phyla Proteobacteria (Pseudomonas, Pseudomonas, Comamonas, Burkholderia, kunye neNeosphingobacterium), iiFirmicutes (Bacillus kunye nePaenibacillus), kunye ne-Actinobacteria (Rhodococcus kunye neArthrobacter) kwi-microbiota yomhlaba zibonakalise amandla okonakalisa iikhompawundi ezahlukeneyo ze-organic. Izifundo ze-metabolic, i-genomics, kunye nohlalutyo lwe-metagenomic zisinceda siqonde ubunzima be-catabolic kunye nokwahluka okukhoyo kwezi ntlobo zobomi zilula, ezinokusetyenziswa ngakumbi kwi-biodegradation esebenzayo. Ubukho bexesha elide bee-PAH bubangele ukuvela kweempawu ezintsha zokubola ngokudluliselwa kwe-gene ethe tye kusetyenziswa izinto ze-genetic ezifana ne-plasmids, ii-transposons, ii-bacteriophages, iziqithi ze-genomic, kunye nezinto ezidibeneyo zokudibanisa. I-systems biology kunye nobunjineli be-genetic be-isolates ezithile okanye ii-model communities (consortia) zinokwenza ukuba i-bioremediation epheleleyo, ekhawulezayo nesebenzayo yezi PAHs ngeziphumo ze-synergistic. Kolu phononongo, sigxila kwiindlela ezahlukeneyo zemetabolism kunye nokwahluka, ukwakheka kwezakhi zofuzo kunye nokwahluka kwazo, kunye neempendulo zeeseli/uhlengahlengiso lwe-naphthalene kunye neebhaktheriya ezitshabalalisa i-naphthalene ezithathelwe indawo. Oku kuya kubonelela ngolwazi lwendalo ukuze kusetyenziswe intsimi kunye nokwenza ngcono ukuxinana ukuze kulungiswe kakuhle i-bioremediation.
Uphuhliso olukhawulezileyo lwamashishini (iikhemikhali zepetroli, ezolimo, amayeza, iidayi zelaphu, izinto zokuthambisa, njl.njl.) lube negalelo ekuchumeni koqoqosho lwehlabathi kunye nokuphucula umgangatho wobomi. Olu phuhliso olukhawulezileyo lubangele ukuveliswa kwenani elikhulu leekhompawundi zendalo ezenziweyo (ii-SOC), ezisetyenziselwa ukuvelisa iimveliso ezahlukeneyo. Ezi khompawundi zangaphandle okanye ii-SOC ziquka ii-polycyclic aromatic hydrocarbons (ii-PAH), izibulali-zinambuzane, izibulali-zinambuzane, iiplastiki, iidayi, amayeza, ii-organophosphates, izithinteli zomlilo, izinyibilikisi zendalo eziguquguqukayo, njl. Zikhutshwa emoyeni, kwiindawo eziphilayo zasemanzini nasemhlabeni apho zinempembelelo ezininzi, zibangela iziphumo ezibi kwiibhayoloji ezahlukeneyo ngokutshintsha iipropati ze-physicochemical kunye nolwakhiwo loluntu (uPetrie et al., 2015; uBernhardt et al., 2017; uSarkar et al., 2020). Izinto ezininzi ezingcolisayo ezinevumba elimnandi zinempembelelo enamandla netshabalalisayo kwiindawo ezininzi eziphilayo/iindawo ezihlala abantu abaninzi (umz. ii-coral reefs, ii-Arctic/Antarctic ice sheets, amachibi aphezulu eentaba, ii-sediments zolwandle olunzulu, njl.njl.) (Jones 2010; Beyer et al. 2020; Nordborg et al. 2020). Izifundo zakutshanje ze-geomicrobiological zibonise ukuba ukulahlwa kwezinto eziphilayo ezenziweyo (umz. izinto ezingcolisayo ezinevumba elimnandi) kunye nezinto eziphuma kuzo phezu kwezakhiwo zokwenziwa (indawo eyakhiweyo) (umz. iindawo zelifa lenkcubeko kunye nezikhumbuzo ezenziwe nge-granite, ilitye, umthi kunye nesinyithi) kukhawulezisa ukubola kwazo (Gadd 2017; Liu et al. 2018). Imisebenzi yabantu inokuqinisa kwaye ibenze mandundu ukubola kwezinto eziphilayo zezikhumbuzo kunye nezakhiwo ngongcoliseko lomoya kunye notshintsho lwemozulu (Liu et al. 2020). Ezi zinto zingcolisayo eziphilayo zisabela kumphunga wamanzi emoyeni kwaye zihlale kwisakhiwo, zibangele ukubola kwezinto ngokwasemzimbeni nangokweekhemikhali. Ukubola kwezinto eziphilayo kubonwa ngokubanzi njengotshintsho olungafunekiyo kwinkangeleko nakwiimpawu zezinto eziphilayo ezibangelwa zizinto eziphilayo ezichaphazela ukugcinwa kwazo (Pochon noJaton, 1967). Isenzo esongezelelekileyo seentsholongwane (i-metabolism) zezi zinto zinokunciphisa ukuqina kwesakhiwo, ukusebenza kakuhle kolondolozo kunye nexabiso lenkcubeko (Gadd, 2017; Liu et al., 2018). Kwelinye icala, kwezinye iimeko, ukuziqhelanisa neentsholongwane kunye nokuphendula kwezi zakhiwo kufunyenwe kuluncedo njengoko zenza ii-biofilms kunye nezinye ii-crusts ezikhuselayo ezinciphisa izinga lokubola/ukubola (Martino, 2016). Ke ngoko, uphuhliso lwezicwangciso zolondolozo oluzinzileyo olusebenzayo lwexesha elide lwezikhumbuzo zamatye, zesinyithi kunye neenkuni lufuna ukuqonda ngokupheleleyo iinkqubo eziphambili ezibandakanyekayo kule nkqubo. Xa kuthelekiswa neenkqubo zendalo (iinkqubo zejoloji, imililo yamahlathi, ukuqhuma kwentaba-mlilo, ukusabela kwezityalo kunye neebhaktheriya), imisebenzi yabantu ibangela ukukhululwa kwemithamo emikhulu ye-polycyclic aromatic hydrocarbons (PAHs) kunye nezinye ii-organic carbon (OC) kwiindawo eziphilayo. Ii-PAH ezininzi ezisetyenziswa kwezolimo (izinambuzane kunye nezibulala-zinambuzane ezifana ne-DDT, i-atrazine, i-carbaryl, i-pentachlorophenol, njl.njl.), ishishini (ioyile ekrwada, udaka/inkunkuma yeoyile, iiplastiki ezifunyenwe kwi-petroleum, ii-PCB, ii-plasticizers, izicoci, izibulali-zinambuzane, izifusi, iziqholo kunye nezigcina-zimo), iimveliso zokhathalelo lomntu (izikrini zelanga, izibulali-zinambuzane, izigxothi zezinambuzane kunye ne-polycyclic musks) kunye nezibhamu (iziqhushumbisi ezifana ne-2,4,6-TNT) zizinto ezinokubangela i-xenobiotics ezinokuthi zichaphazele impilo yeplanethi (Srogi, 2007; Vamsee-Krishna kunye noPhale, 2008; Petrie et al., 2015). Olu luhlu lunokwandiswa ukuze lubandakanye iikhompawundi ezifunyenwe kwi-petroleum (iioyile zepetroli, ii-lubricants, ii-asphaltenes), ii-bioplastics ezinobunzima obuphezulu beemolekyuli, kunye nee-ionic liquids (Amde et al., 2015). Itheyibhile 1 idwelisa uluhlu lweentlobo ngeentlobo zezingcolisi ezinuka kamnandi kunye nokusetyenziswa kwazo kumashishini ahlukeneyo. Kwiminyaka yakutshanje, ukukhutshwa kwezinto eziphilayo eziguquguqukayo, kunye ne-carbon dioxide kunye nezinye iigesi ze-greenhouse, kuye kwaqala ukwanda (Dvorak et al., 2017). Nangona kunjalo, iimpembelelo ze-anthropogenic zidlula kakhulu ezendalo. Ukongeza, sifumanise ukuba inani lee-SOC zihlala kwiindawo ezininzi zendalo kwaye zichongiwe njengezingcolisi ezivelayo ezinemiphumo emibi kwi-biomes (Umfanekiso 1). Iiarhente zendalo ezifana ne-United States Environmental Protection Agency (USEPA) zifake uninzi lwezi zingcolisi kuluhlu lwazo oluphambili ngenxa yeempawu zazo ze-cytotoxic, genotoxic, mutagenic, kunye ne-carcinogenic. Ke ngoko, imithetho engqongqo yokulahla kunye namaqhinga asebenzayo okunyanga/ukususa inkunkuma kwiindawo zendalo ezingcolisiweyo iyafuneka. Iindlela ezahlukeneyo zonyango zomzimba nezekhemikhali ezifana ne-pyrolysis, unyango lwe-oxidative thermal, umoya ophumayo, ukuzalisa inkunkuma, ukutshisa, njl. azisebenzi kwaye zibiza kakhulu kwaye zivelisa iimveliso ezibolayo, ezinobuthi kwaye kunzima ukuziphatha. Njengoko ulwazi olukhulayo ngokusingqongileyo kwihlabathi liphela, iintsholongwane ezikwaziyo ukonakalisa ezi zinto zingcolisayo kunye nezinto eziphuma kuzo (ezifana ne-halogenated, i-nitro, i-alkyl kunye/okanye i-methyl) zitsala ingqalelo eyandayo (Fennell et al., 2004; Haritash kunye noKaushik, 2009; Phale et al., 2020; Sarkar et al., 2020; Schwanemann et al., 2020). Ukusetyenziswa kwezi ntsholongwane zemveli zodwa okanye kwiinkcubeko ezixutyiweyo (iikholoni) ukususa izinto ezingcolisayo ezinevumba elimnandi kuneengenelo ngokubhekiselele kukhuseleko lokusingqongileyo, iindleko, ukusebenza kakuhle, ukusebenza kakuhle, kunye nokuzinza. Abaphandi bakwahlola ukuhlanganiswa kweenkqubo zeentsholongwane kunye neendlela ze-electrochemical redox, ezizezi iinkqubo ze-bioelectrochemical (BES), njengetekhnoloji ethembisayo yonyango/ukususa izinto ezingcolisayo (Huang et al., 2011). Itekhnoloji ye-BES itsale ingqalelo ekhulayo ngenxa yokusebenza kwayo okuphezulu, iindleko eziphantsi, ukhuseleko lokusingqongileyo, ukusebenza kobushushu begumbi, izixhobo ezihambelana ne-bio, kunye nokukwazi ukubuyisa iimveliso ezixabisekileyo (umz., umbane, ipetroli, kunye neekhemikhali) (Pant et al., 2012; Nazari et al., 2020). Ukufika kwe-high-throughput genome sequencing kunye nezixhobo/iindlela ze-omics kubonelele ngolwazi olutsha malunga nolawulo lwe-genetic, i-proteomics, kunye ne-fluxomics yempendulo ye-microorganisms ezahlukeneyo eziwohlokayo. Ukudibanisa ezi zixhobo kunye ne-systems biology kuye kwaphucula ngakumbi ukuqonda kwethu ukukhethwa kunye nokulungiswa kakuhle kweendlela ze-catabolic ezijoliswe kuzo kwi-microorganisms (oko kukuthi, uyilo lwe-metabolic) ukuze kufezekiswe i-biodegradation esebenzayo nesebenzayo. Ukuyila amaqhinga okulungisa i-bioremediation asebenzayo kusetyenziswa ii-microorganisms ezifanelekileyo, kufuneka siqonde amandla e-biochemical, ulwahluko lwe-metabolic, ukwakheka kwe-genetic, kunye ne-ecology (autoecology/synecology) yee-microorganisms.
Umzobo 1. Imithombo kunye neendlela ze-PAHs eziphantsi kweemolekyuli kwiindawo ezahlukeneyo zendalo kunye nezinto ezahlukeneyo ezichaphazela i-biota. Imigca eqhekekileyo imele ukusebenzisana phakathi kwezinto zendalo.
Kolu phononongo, sizame ukushwankathela idatha malunga nokuwohloka kwee-PAH ezilula ezifana ne-naphthalene kunye ne-naphthalenes ezitshintshiweyo ziibhaktiriya ezahlukeneyo ezigubungela iindlela ze-metabolic kunye nokwahluka, ii-enzymes ezibandakanyekayo ekuwohlokeni, ukwakheka/umxholo wejini kunye nokwahluka, iimpendulo zeseli kunye nemiba eyahlukeneyo yokulungiswa kwe-bio. Ukuqonda amanqanaba e-biochemical kunye neemolekyuli kuya kunceda ekuchongeni iintlobo ezifanelekileyo zomninimzi kunye nobunjineli bazo obuqhubekayo be-genetic ukuze kulungiswe ngempumelelo ezo zinto zingcolisayo ziphambili. Oku kuya kunceda ekuphuhliseni amaqhinga okusekwa kwe-bacterial consortia yendawo ethile ukuze kulungiswe ngempumelelo i-bioremediation.
Ukubakho kwenani elikhulu leekhompawundi ezinobungozi nezinobungozi ze-aromatic (okwanelisa umthetho weHuckel 4n + 2π electrons, n = 1, 2, 3, …) kubeka umngcipheko omkhulu kwiindlela ezahlukeneyo zokusingqongileyo ezifana nomoya, umhlaba, i-sediments, kunye nomphezulu kunye namanzi angaphantsi komhlaba (Puglisi et al., 2007). Ezi khompawundi zineeringi ze-benzene enye (i-monocyclic) okanye iiringi ze-benzene ezininzi (i-polycyclic) ezicwangciswe ngendlela ethe ngqo, e-angular okanye yeqela kwaye zibonisa uzinzo (ukuzinza/ukungazinzi) kwimeko-bume ngenxa yamandla aphezulu e-resonance angalunganga kunye nokungangeni (ukungangeni), okunokuchazwa kukungazinzi kwazo kunye nemeko enciphileyo. Xa indandatho ye-aromatic ithathelwa indawo yi-methyl (-CH3), i-carboxyl (-COOH), i-hydroxyl (-OH), okanye amaqela e-sulfonate (-HSO3), iba nozinzo ngakumbi, inobuhlobo obuqinileyo kwii-macromolecules, kwaye iqokelelana kwiinkqubo zebhayoloji (Seo et al., 2009; Phale et al., 2020). Ezinye ii-polycyclic aromatic hydrocarbons (LMWAHs) ezinobunzima obuphantsi beemolekyuli, ezifana ne-naphthalene kunye ne-derivatives yayo [methylnaphthalene, naphthoic acid, naphthalenesulfonate, kunye ne-1-naphthyl N-methylcarbamate (carbaryl)], zibandakanyiwe kuluhlu lwezinto ezingcolisayo ze-organic eziphambili yi-US Environmental Protection Agency njenge-genotoxic, mutagenic, kunye/okanye i-carcinogenic (Cerniglia, 1984). Ukukhululwa kolu didi lwee-NM-PAHs kwindalo esingqongileyo kunokubangela ukuqokelelwa kwezinto eziphilayo kwezi zinto kuzo zonke iinqanaba zekhonkco lokutya, nto leyo echaphazela impilo yeendawo ezihlala kuzo (Binkova et al., 2000; Srogi, 2007; Quinn et al., 2009).
Imithombo kunye neendlela ze-PAHs ukuya kwi-biota ngokuyintloko kukufuduka kunye nokusebenzisana phakathi kwezinto ezahlukeneyo ze-ecosystem ezifana nomhlaba, amanzi angaphantsi komhlaba, amanzi angaphezulu komhlaba, izityalo kunye nomoya (Arey no-Atkinson, 2003). Umfanekiso 1 ubonisa ukusebenzisana kunye nokusasazwa kwee-PAHs ezahlukeneyo ezinobunzima obuphantsi beemolekyuli kwiindawo ze-ecosystem kunye neendlela zazo zokuya kwi-biota/ukuvezwa kwabantu. Ii-PAHs zifakwa kwiindawo eziphezulu ngenxa yongcoliseko lomoya kunye nokufuduka (ukukhukuliseka) kokukhutshwa kwezithuthi, iigesi zokukhupha umoya kwimizi-mveliso (igesi yamalahle, ukutsha kunye nemveliso ye-coke) kunye nokufakwa kwazo. Imisebenzi yemizi-mveliso efana nokwenziwa kweelaphu zokwenziwa, iidayi kunye neepeyinti; ukugcinwa kwemithi; ukucubungula irabha; imisebenzi yokuvelisa isamente; imveliso yezibulala-zinambuzane; kunye nokusetyenziswa kwezolimo ziindawo eziphambili ze-PAHs kwiinkqubo zomhlaba kunye nezasemanzini (Bamforth noSingleton, 2005; Wick et al., 2011). Izifundo zibonise ukuba umhlaba okwiindawo ezisemaphandleni nasezidolophini, kufutshane neendlela ezinkulu, nakwizixeko ezikhulu usengozini enkulu ye-polycyclic aromatic hydrocarbons (ii-PAH) ngenxa yokukhutshwa kwegesi okuvela kwizityalo zamandla, ukufudumeza izindlu, imithwalo yezithuthi zomoya kunye neendlela, kunye nemisebenzi yokwakha (uSuman et al., 2016). (2008) ibonise ukuba ii-PAH ezikumhlaba okufutshane neendlela eNew Orleans, eLouisiana, e-USA zaziphezulu njenge-7189 μg/kg, ngelixa kwindawo evulekileyo, zaziyi-2404 μg/kg kuphela. Ngokufanayo, amanqanaba e-PAH aphezulu njenge-300 μg/kg axeliwe kwiindawo ezikufutshane neendawo zokufaka igesi yamalahle kwizixeko ezininzi zase-US (uKanaly noHarayama, 2000; uBamforth noSingleton, 2005). Umhlaba ovela kwizixeko ezahlukeneyo zaseIndiya ezifana neDelhi (Sharma et al., 2008), Agra (Dubey et al., 2014), Mumbai (Kulkarni kunye neVenkataraman, 2000) kunye neVisakhapatnam (Kulkarni et al., 2014) kuye kwaxelwa ukuba uqulathe ubuninzi be-PAHs. Iikhompawundi zevumba elimnandi zifunxwa lula kwiisuntswana zomhlaba, izinto eziphilayo kunye neeminerali zodongwe, ngaloo ndlela zibe zizinki ezinkulu zekhabhoni kwiindawo eziphilayo (Srogi, 2007; Peng et al., 2008). Imithombo ephambili ye-PAHs kwiindawo eziphilayo zasemanzini yimvula (imvula emanzi/eyomileyo kunye nomphunga wamanzi), amanzi aphuma ezidolophini, ukukhupha amanzi amdaka, ukuphinda kufakwe amanzi angaphantsi komhlaba njl.njl. (Srogi, 2007). Kuqikelelwa ukuba malunga ne-80% ye-PAHs kwiindawo eziphilayo zaselwandle zivela kwimvula, ukutsalwa kwenkunkuma, kunye nokukhupha inkunkuma (Motelay-Massei et al., 2006; Srogi, 2007). Ubuninzi bee-PAHs emanzini angaphezulu okanye i-leachate evela kwiindawo zokulahla inkunkuma eqinileyo ekugqibeleni ivuza emanzini angaphantsi komhlaba, nto leyo ebeka umngcipheko omkhulu kwimpilo yoluntu kuba ngaphezulu kwama-70% abemi baseMzantsi naseMzantsi-mpuma Asia basela amanzi angaphantsi komhlaba (Duttagupta et al., 2019). Uphononongo lwakutshanje olwenziwe nguDuttagupta et al. (2020) lohlalutyo lomlambo (32) kunye namanzi angaphantsi komhlaba (235) oluvela eWest Bengal, eIndiya, lufumanise ukuba i-53% yabemi basezidolophini kunye ne-44% yabemi basemaphandleni (bebonke abemi abazizigidi ezingama-20) banokuchaphazeleka yi-naphthalene (4.9–10.6 μg/L) kunye nezinto eziphuma kuyo. Iipateni ezahlukeneyo zokusetyenziswa komhlaba kunye nokwanda kokukhutshwa kwamanzi angaphantsi komhlaba kuthathwa njengezona zinto ziphambili ezilawula ukuthuthwa ngokuthe nkqo (ukuhambela) kwee-PAHs ezinobunzima obuphantsi bemolekyuli emanzini angaphantsi komhlaba. Ukuchitheka kwamanzi amdaka ezolimo, amanzi amdaka kamasipala namashishini, kunye nokukhutshwa kwamanzi amdaka/inkunkuma kufunyenwe kuchaphazeleka zii-PAHs kwimisele yemilambo kunye nenkunkuma engaphantsi komhlaba. Ukuna kwemvula emoyeni kuyayinyusa ngakumbi i-PAH. Ubuninzi be-PAH kunye ne-alkyl derivatives yazo (ezingama-51 zizonke) zibikwe kwimilambo/kwiindawo zamanzi kwihlabathi liphela, njengoMlambo iFraser, uMlambo iLouan, uMlambo iDenso, uMlambo iMissouri, uMlambo iAnacostia, uMlambo iEbro, kunye noMlambo iDelaware (Yunker et al., 2002; Motelay-Massei et al., 2006; Li et al., 2010; Amoako et al., 2011; Kim et al., 2018). Kwiindawo ezisele zoMlambo iGanges, i-naphthalene kunye ne-phenanthrene zifunyenwe zezona zibalulekileyo (zifunyenwe kwi-70% yeesampuli) (Duttagupta et al., 2019). Ngaphezu koko, izifundo zibonise ukuba i-chlorination yamanzi okusela inokukhokelela ekwakhiweni kwee-PAH ezine-oxygen kunye ne-chlorine ezinobungozi ngakumbi (uManoli noSamara, 1999). Ii-PAH ziqokelelana kwiinkozo, iziqhamo kunye nemifuno ngenxa yokufunxwa zizityalo kumhlaba ongcolileyo, amanzi angaphantsi komhlaba kunye nemvula (Fismes et al., 2002). Izinto ezininzi eziphilayo zasemanzini ezifana neentlanzi, ii-mussels, ii-clams kunye nee-shrimp zingcoliswe zii-PAH ngokutya ukutya okungcolisiweyo kunye namanzi olwandle, kunye nezicubu kunye nolusu (Mackay kunye noFraser, 2000). Iindlela zokupheka/zokucubungula ezifana nokugrila, ukurosta, ukutshaya, ukuqhotsa, ukomisa, ukubhaka kunye nokupheka ngamalahle nazo zinokukhokelela kumanani amaninzi ee-PAH ekutyeni. Oku kuxhomekeke kakhulu ekukhetheni izinto zokutshaya, umxholo we-phenolic/aromatic hydrocarbon, inkqubo yokupheka, uhlobo lwesifudumezi, umxholo wokufuma, unikezelo lwe-oxygen kunye nobushushu bokutsha (Guillén et al., 2000; Gomes et al., 2013). Ii-polycyclic aromatic hydrocarbons (ii-PAHs) nazo zifunyenwe kubisi kumanqanaba ahlukeneyo (0.75–2.1 mg/L) (Girelli et al., 2014). Ukuqokelelana kwezi PAH ekutyeni kuxhomekeke kwiimpawu ze-physicochemical zokutya, ngelixa iziphumo zazo ezinobungozi zinxulumene nemisebenzi yomzimba, umsebenzi we-metabolic, ukufunxwa, ukusasazwa kunye nokusasazwa komzimba (Mechini et al., 2011).
Ubuthi kunye nemiphumo eyingozi ye-polycyclic aromatic hydrocarbons (ii-PAH) bezisaziwa ixesha elide (iCherniglia, 1984). Ii-polycyclic aromatic hydrocarbons ezinobunzima obuphantsi be-molecular (ii-LMW-PAHs) (iindandatho ezimbini ukuya kwezintathu) zinokubophelela ngokudibeneyo kwii-macromolecules ezahlukeneyo ezifana ne-DNA, i-RNA kunye neeproteni kwaye zibangela umhlaza (i-Santarelli et al., 2008). Ngenxa yendalo yazo yokungathandi amanzi, zahlulwe zii-lipid membranes. Kubantu, ii-cytochrome P450 monooxygenases zi-oxidize ii-PAHs zibe zii-epoxides, ezinye zazo zisabela kakhulu (umz., i-baediol epoxide) kwaye zinokukhokelela ekuguqulweni kweeseli eziqhelekileyo zibe zezo zinobungozi (i-Marston et al., 2001). Ukongeza, iimveliso zotshintsho lwee-PAHs ezifana nee-quinones, ii-phenols, ii-epoxides, ii-diols, njl.njl. zinobuthi ngaphezu kwee-compounds ezizalayo. Ezinye ii-PAH kunye ne-metabolism yazo zinokuthi zichaphazele iihomoni kunye nee-enzymes ezahlukeneyo kwi-metabolism, ngaloo ndlela zichaphazele kakubi ukukhula, inkqubo ye-nervous central, iinkqubo zokuzala kunye nezokuzikhusela (Swetha kunye noPhale, 2005; Vamsee-Krishna et al., 2006; Oostingh et al., 2008). Ukuvezwa kwexesha elifutshane kwi-PAHs ezinobunzima obuphantsi beemolekyuli kuye kwaxelwa ukuba kubangela ukuphazamiseka komsebenzi wemiphunga kunye ne-thrombosis kubantu abane-asthma kwaye kwandisa umngcipheko womhlaza wesikhumba, wemiphunga, wesinyi kunye nowesisu (Olsson et al., 2010; Diggs et al., 2011). Izifundo zezilwanyana zikwabonise ukuba ukuvezwa kwe-PAH kunokuba nemiphumo emibi kumsebenzi wokuzala kunye nophuhliso kwaye kunokubangela i-cataracts, umonakalo wezintso nesibindi, kunye ne-jaundice. Iimveliso ezahlukeneyo ze-PAH biotransformation ezifana nee-diols, ii-epoxides, ii-quinones kunye nee-free radicals (ii-cations) zibonakalisiwe ukuba zenza i-DNA adducts. Kuye kwabonakala ukuba ii-adducts ezizinzileyo zitshintsha umatshini wokuphindaphinda i-DNA, ngelixa ii-adducts ezingazinzanga zinokususa i-DNA (ikakhulukazi ibe yi-adenine kwaye ngamanye amaxesha ibe yi-guanine); zombini zinokuvelisa iimpazamo ezikhokelela kwiinguqu (Schweigert et al. 2001). Ukongeza, ii-quinones (benzo-/pan-) zinokuvelisa iintlobo ze-oxygen ezisebenzayo (ROS), zibangele umonakalo obulalayo kwi-DNA nakwezinye ii-macromolecules, ngaloo ndlela zichaphazela ukusebenza/ukuphila kwezicubu (Ewa kunye noDanuta 2017). Ukuvezwa rhoqo kumanqanaba aphantsi e-pyrene, biphenyl kunye ne-naphthalene kuye kwaxelwa ukuba kubangela umhlaza kwizilwanyana ezivavanyiweyo (Diggs et al. 2012). Ngenxa yobuthi bazo obubulalayo, ukucocwa/ukususwa kwezi PAH kwiindawo ezichaphazelekayo/ezingcolisiweyo kuyinto ephambili.
Iindlela ezahlukeneyo zomzimba nezekhemikhali zisetyenzisiwe ukususa ii-PAH kwiindawo/kwindawo ezingcolisiweyo. Iinkqubo ezinje ngokutshisa, ukususa ichlorination, i-UV oxidation, ukulungiswa, kunye nokukhupha i-solvent zineengxaki ezininzi, kubandakanya ukwenziwa kweemveliso ezinobungozi, ubunzima benkqubo, imiba yokhuseleko kunye nemithetho, ukusebenza okuphantsi, kunye neendleko eziphezulu. Nangona kunjalo, i-microbial biodegradation (ebizwa ngokuba yi-bioremediation) yindlela ethembisayo eyahlukileyo ebandakanya ukusetyenziswa kwee-microorganisms ngendlela yeenkcubeko ezicocekileyo okanye iikholoni. Xa kuthelekiswa neendlela zomzimba nezekhemikhali, le nkqubo inobuhlobo nokusingqongileyo, ayingenisi, ixabisa kancinci, kwaye iyaqhubeka. I-Bioremediation ingenziwa kwindawo echaphazelekayo (kwindawo) okanye kwindawo elungiselelwe ngokukodwa (ex situ) kwaye ke ngoko ithathwa njengendlela yokulungisa ezinzileyo ngakumbi kuneendlela zemveli zomzimba nezekhemikhali (Juhasz noNaidu, 2000; Andreoni noGianfreda, 2007; Megharaj et al., 2011; Phale et al., 2020; Sarkar et al., 2020).
Ukuqonda amanyathelo e-metabolism eentsholongwane abandakanyeka ekonakaleni kwezinto ezingcolisayo ezinevumba elimnandi kunefuthe elikhulu kwezesayensi nakwezoqoqosho ekuzinzeni kwendalo kunye nokusingqongileyo. I-2.1 × 1018 grams yekhabhoni (C) eqikelelweyo igcinwa kwi-sediments kunye nee-organic compounds (oko kukuthi, ioyile, igesi yendalo, kunye namalahle, oko kukuthi, amafutha e-fossil) kwihlabathi liphela, okwenza igalelo elikhulu kumjikelo wekhabhoni yehlabathi. Nangona kunjalo, ukukhula ngokukhawuleza kwemizi-mveliso, ukukhutshwa kwamafutha e-fossil, kunye nemisebenzi yabantu kuyayiphelisa le ndawo yokugcina ikhabhoni ye-lithospheric, ikhupha i-5.5 × 1015 g ye-organic carbon (njengezinto ezingcolisayo) emoyeni minyaka le (Gonzalez-Gaya et al., 2019). Uninzi lwale khabhoni ye-organic lungena kwiindawo eziphilayo zomhlaba naselwandle ngokuthuthwa, ukuthuthwa, kunye nokuphuma kwamanzi. Ukongeza, izinto ezintsha ezingcolisayo ezenziweyo ezivela kwii-fossil fuels, ezifana neeplastiki, ii-plasticizers kunye neziqinisi zeplastiki (ii-phthalates kunye nee-isomers zazo), zingcolisa kakhulu iindawo eziphilayo zaselwandle, zomhlaba nasemanzini kunye ne-biota yazo, ngaloo ndlela zikhulisa umngcipheko wemozulu yehlabathi. Iindidi ezahlukeneyo zee-microplastics, ii-nanoplastics, iziqwenga zeplastiki kunye neemveliso zazo ze-monomer ezinetyhefu ezivela kwi-polyethylene terephthalate (PET) ziye zaqokelelana kuLwandlekazi lwePasifiki phakathi koMntla Melika kunye noMzantsi-mpuma we-Asia, zenza "iGreat Pacific Garbage Patch", zenzakalisa ubomi baselwandle (Newell et al., 2020). Izifundo zesayensi ziye zabonisa ukuba akunakwenzeka ukususa ungcoliseko/inkunkuma enjalo nangayiphi na indlela ebonakalayo okanye yekhemikhali. Kule meko, ii-microorganisms eziluncedo kakhulu zezo zikwaziyo ukunyibilikisa ungcoliseko nge-oxidative zibe yi-carbon dioxide, amandla eekhemikhali kunye nezinye iimveliso ezingezizo ezinobungozi ekugqibeleni zingena kwezinye iinkqubo zokujikeleza kwezakhamzimba (H, O, N, S, P, Fe, njl.njl.). Ke ngoko, ukuqonda i-microbial ecophysiology ye-aromatic pollutant mineralization kunye nolawulo lwayo lokusingqongileyo kubalulekile ekuvavanyeni umjikelo we-microbial carbon, i-net carbon budget kunye nemingcipheko yemozulu yexesha elizayo. Ngenxa yesidingo esingxamisekileyo sokususa ezo zinto kwindalo esingqongileyo, kuye kwavela amashishini ahlukeneyo e-eco-industry agxile kubuchwepheshe obucocekileyo. Kungenjalo, ukubekwa ixabiso kweekhemikhali zenkunkuma/inkunkuma yemizi-mveliso eziqokelelwe kwiindawo eziphilayo (oko kukuthi indlela yokulahla inkunkuma ukuya kubutyebi) kuthathwa njengenye yeentsika zoqoqosho olujikelezayo kunye neenjongo zophuhliso oluzinzileyo (Close et al., 2012). Ke ngoko, ukuqonda imiba ye-metabolic, i-enzymatic kunye ne-genetic yala maqela anokuwohloka kubaluleke kakhulu ekususweni nasekulungisweni kwe-bioremediation ngokufanelekileyo kwezo zinto zingcolisayo zinuka kamnandi.
Phakathi kwezinto ezininzi ezingcolisayo, sinikela ingqalelo ekhethekileyo kwii-PAH ezinobunzima obuphantsi beemolekyuli ezifana ne-naphthalene kunye nee-naphthalene ezisetyenzisiweyo. Ezi zinto ziyinxalenye ephambili yamafutha aphuma kwi-petroleum, iidayi zelaphu, iimveliso zabathengi, izibulali-zinambuzane (iibhola zeemoth kunye nezixovuli zezinambuzane), iiplastiki kunye neetannins kwaye ke ngoko zixhaphake kwiindawo ezininzi zendalo (Preuss et al., 2003). Iingxelo zakutshanje zibonisa ukuqokelelwa kwamanqanaba e-naphthalene kwi-aquifer sediments, amanzi angaphantsi komhlaba kunye nomhlaba ongaphantsi komhlaba, iindawo ze-vadose kunye nemida yomlambo, nto leyo ebonisa ukuba iqokelelana kwindalo esingqongileyo (Duttagupta et al., 2019, 2020). Itheyibhile 2 ishwankathela iipropati ze-physicochemical, usetyenziso kunye nemiphumo yempilo ye-naphthalene kunye nezinto eziphuma kuyo. Xa kuthelekiswa nezinye ii-PAH ezinobunzima beemolekyuli eziphezulu, i-naphthalene kunye nezinto eziphuma kuyo azinawo umoya kangako, azinyibiliki emanzini kwaye zisasazeke kakhulu kwiindawo zendalo, ngoko ke zihlala zisetyenziswa njengee-substrates zemodeli zokufunda i-metabolism, i-genetics kunye nokwahluka kwe-metabolic ye-PAHs. Inani elikhulu leentsholongwane ziyakwazi ukunyibilikisa i-naphthalene kunye nezinto eziphuma kuyo, kwaye ulwazi olupheleleyo luyafumaneka malunga neendlela zazo ze-metabolic, ii-enzymes kunye neempawu zolawulo (Mallick et al., 2011; Phale et al., 2019, 2020). Ukongeza, i-naphthalene kunye nezinto eziphuma kuyo zibizwa ngokuba zii-prototype compounds zovavanyo longcoliseko lokusingqongileyo ngenxa yobuninzi bazo obuphezulu kunye nokufumaneka kwazo. I-US Environmental Protection Agency iqikelela ukuba amanqanaba aphakathi e-naphthalene yi-5.19 μg nge-cubic meter nganye kumsi wecuba, ngokuyintloko ngenxa yokutsha okungaphelelanga, kunye ne-7.8 ukuya kwi-46 μg evela kumsi osecaleni, ngelixa ukuvezwa kwi-creosote kunye ne-naphthalene kuphindwe ka-100 ukuya kwi-10,000 (Preuss et al. 2003). I-Naphthalene ngokukodwa ifunyenwe inetyhefu yokuphefumla kunye ne-carcinogenicity yeentlobo, ingingqi, kunye nesondo. Ngokusekelwe kwizifundo zezilwanyana, i-International Agency for Research on Cancer (IARC) ibeke i-naphthalene kwindawo yayo njenge "inokubangela umhlaza ebantwini" (iQela 2B)1. Ukuvezwa kwi-naphthalenes ezifakwe endaweni yayo, ngokuyintloko ngokuphefumla okanye ngokufakwa ngomlomo (ngomlomo), kubangela ukwenzakala kwezicubu zemiphunga kwaye kwandisa ukwanda kweethumba zemiphunga kwiimpuku nakwiimpuku (iNkqubo yeSizwe yeToxicology 2). Iziphumo ezibukhali ziquka isicaphucaphu, ukuhlanza, iintlungu zesisu, urhudo, intloko ebuhlungu, ukudideka, ukubila kakhulu, umkhuhlane, i-tachycardia, njl. Kwelinye icala, i-carbamate insecticide carbaryl (1-naphthyl N-methylcarbamate) ibikwe njengetyhefu kwizilwanyana ezingenamqolo emanzini, ii-amphibians, iinyosi zobusi kunye nabantu kwaye ibonakalisiwe ukuba ithintela i-acetylcholinesterase ebangela ukukhubazeka (Smulders et al., 2003; Bulen and Distel, 2011). Ke ngoko, ukuqonda iindlela zokuwohloka kweentsholongwane, ulawulo lwezakhi zofuzo, i-enzymatic kunye neempendulo zeseli kubalulekile ekuphuhliseni amaqhinga okulungisa izinto eziphilayo kwiindawo ezingcolisiweyo.
Itheyibhile 2. Ulwazi oluneenkcukacha malunga neempawu ze-physicochemical, ukusetyenziswa, iindlela zokuchonga kunye nezifo ezinxulumene ne-naphthalene kunye nezinto eziphuma kuyo.
Kwiindawo ezingcolileyo, ukungcola okubangelwa yi-hydrophobic kunye ne-lipophilic aromatic kunokubangela iziphumo ezahlukeneyo zeseli kwi-microbiome yokusingqongileyo (uluntu), njengotshintsho kwi-membrane fluidity, i-membrane permeability, ukudumba kwe-lipid bilayer, ukuphazamiseka kokudluliselwa kwamandla (i-electron transport chain/proton motivation force), kunye nomsebenzi weeproteni ezinxulumene ne-membrane (Sikkema et al., 1995). Ukongeza, ezinye izinto ezinyibilikayo ezifana ne-catechols kunye ne-quinones zivelisa iintlobo ze-oxygen ezisebenzayo (i-ROS) kwaye zenze i-adducts ene-DNA kunye neeproteni (Penning et al., 1999). Ke ngoko, ubuninzi beekhompawundi ezinjalo kwiindawo eziphilayo bunexinzelelo olukhethiweyo kuluntu lwee-microbial ukuba zibe zii-degraders ezisebenzayo kumanqanaba ahlukeneyo e-physiological, kubandakanya ukufunxwa/ukuthutha, ukuguqulwa kwangaphakathi kweseli, ukuhlanganiswa/ukusetyenziswa, kunye nokwahlulwahlulwa.
Uphando lweRibosomal Database Project-II (RDP-II) lubonise ukuba iintlobo zebhaktiriya ezingama-926 zizonke zahlulwe kwiinkcubeko zemidiya okanye zokufunxwa kwe-naphthalene okanye izinto eziphuma kuyo. Iqela leProteobacteria lalinamanani aphezulu abameli (n = 755), lilandelwa yiFirmicutes (52), iBacteroidetes (43), iActinobacteria (39), iTenericutes (10), kunye neebhaktiriya ezingahlelwanga (8) (Umfanekiso 2). Abameli be-γ-Proteobacteria (Pseudomonadales kunye neXanthomonadales) babelawula onke amaqela eGram-negative anomxholo ophezulu weG+C (54%), ngelixa iiClostridiales kunye neBacillales (30%) zazingamaqela eGram-positive anomxholo ophantsi weG+C. IiPseudomonas (ezinenani eliphezulu, iintlobo ezingama-338) zixelwe ukuba ziyakwazi ukonakalisa i-naphthalene kunye ne-methyl derivatives yayo kwiindawo ezahlukeneyo zendalo ezingcolisiweyo (i-coal tar, i-petroleum, i-oyile ekrwada, udaka, ukuchitheka kweoyile, amanzi amdaka, inkunkuma yendalo kunye neendawo zokulahla inkunkuma) kunye nakwiindawo zendalo ezingasebenziyo (umhlaba, imilambo, inkunkuma kunye namanzi angaphantsi komhlaba) (Umfanekiso 2). Ngaphezu koko, izifundo zokutyebisa kunye nohlalutyo lwe-metagenomic kwezinye zezi ndawo zityhile ukuba iintlobo zeLegionella kunye neClostridium ezingakhuliswanga zinokuba namandla okubola, nto leyo ebonisa imfuneko yokukhulisa ezi bhaktheriya ukuze kufundwe iindlela ezintsha kunye nokwahluka kwe-metabolic.
Umzobo 2. Ukwahlukahlukana kwe-taxonomic kunye nokusasazwa kwe-ecological kwabameli beebhaktheriya kwiindawo ezingcoliswe yi-naphthalene kunye ne-naphthalene derivatives.
Phakathi kweentsholongwane ezahlukeneyo ezibola i-hydrocarbon, uninzi lwazo luyakwazi ukonakalisa i-naphthalene njengomthombo wekhabhoni kunye namandla. Ulandelelwano lweziganeko ezibandakanyeka kwi-metabolism ye-naphthalene luchazwe kwi-Pseudomonas sp. (iintlobo: NCIB 9816-4, G7, AK-5, PMD-1 kunye neCSV86), Pseudomonas stutzeri AN10, Pseudomonas fluorescens PC20 kunye nezinye iintlobo (ND6 kunye ne-AS1) (Mahajan et al., 1994; Resnick et al., 1996; Annweiler et al., 2000; Basu et al., 2003; Dennis and Zylstra, 2004; Sota et al., 2006; I-Metabolism iqalwa yi-dioxygenase ene-multicomponent [naphthalene dioxygenase (NDO), i-ring hydroxylating dioxygenase] ebangela i-oxidation kwenye yeendandatho ze-aromatic ze-naphthalene isebenzisa i-molecule oxygen njengenye i-substrate, iguqula i-naphthalene ibe yi-cis-naphthalenediol (Umfanekiso 3). I-Cis-dihydrodiol iguqulwa ibe yi-1,2-dihydroxynaphthalene yi i-dehydrogenase. I-dioxygenase eqhekeza i-ring-cleaving, i-1,2-dihydroxynaphthalene dioxygenase (12DHNDO), iguqula i-1,2-dihydroxynaphthalene ibe yi-2-hydroxychromene-2-carboxylic acid. I-Enzymatic cis-trans isomerization ivelisa i-trans-o-hydroxybenzylidenepyruvate, eqhekeka yi-hydratase aldolase ibe yi-salicylic aldehyde kunye ne-pyruvate. I-organic acid pyruvate yayiyi-compound yokuqala ye-C3 ethathwe kwi-naphthalene carbon skeleton kwaye yaqondiswa kwindlela ephakathi yekhabhoni. Ukongeza, i-NAD+-dependent salicylaldehyde dehydrogenase iguqula i-salicylaldehyde ibe yi-salicylic acid. I-metabolism kweli nqanaba ibizwa ngokuba "yindlela ephezulu" yokubola kwe-naphthalene. Le ndlela ixhaphake kakhulu kwiibhaktheriya ezininzi ezibola i-naphthalene. Nangona kunjalo, kukho izinto ezimbalwa ezingaqhelekanga; umzekelo, kwi-thermophilic Bacillus hamburgii 2, ukubola kwe-naphthalene kuqaliswa yi-naphthalene. I-2,3-dioxygenase ukwenza i-2,3-dihydroxynaphthalene (Annweiler et al., 2000).
Umfanekiso 3. Iindlela ze-naphthalene, i-methylnaphthalene, i-naphthoic acid, kunye nokudilizwa kwe-carbaryl. Amanani ajikeleziweyo amele ii-enzymes ezinoxanduva lokuguqulwa ngokulandelelana kwe-naphthalene kunye nezinto eziphuma kuyo zibe ziimveliso ezilandelayo. 1 — i-naphthalene dioxygenase (NDO); 2, i-cis-dihydrodiol dehydrogenase; 3, i-1,2-dihydroxynaphthalene dioxygenase; 4, i-2-hydroxychromene-2-carboxylic acid isomerase; 5, i-trans-O-hydroxybenzylidenepyruvate hydratase aldolase; 6, i-salicylaldehyde dehydrogenase; 7, i-salicylate 1-hydroxylase; 8, i-catechol 2,3-dioxygenase (C23DO); 9, i-2-hydroxymuconate semialdehyde dehydrogenase; 10, i-2-oxopent-4-enoate hydratase; 11, i-4-hydroxy-2-oxopentanoate aldolase; 12, i-acetaldehyde dehydrogenase; 13, i-catechol-1,2-dioxygenase (C12DO); 14, i-muconate cycloisomerase; 15, i-muconolactone delta-isomerase; 16, i-β-ketoadipatenollactone hydrolase; 17, i-β-ketoadipate succinyl-CoA transferase; 18, i-β-ketoadipate-CoA thiolase; 19, i-succinyl-CoA: i-acetyl-CoA succinyltransferase; 20, i-salicylate 5-hydroxylase; 21 – i-gentisate 1,2-dioxygenase (GDO); 22, i-maleylpyruvate isomerase; 23, i-fumarylpyruvate hydrolase; 24, i-methylnaphthalene hydroxylase (NDO); 25, i-hydroxymethylnaphthalene dehydrogenase; 26, i-naphthaldehyde dehydrogenase; 27, i-3-formylsalicylic acid oxidase; 28, i-hydroxyisophthalate decarboxylase; 29, i-carbaryl hydrolase (CH); 30, i-1-naphthol-2-hydroxylase.
Ngokuxhomekeke kwindalo kunye nokwakheka kwayo kwemfuza, i-salicylic acid ephumayo iphinda ixutywe ngendlela ye-catechol kusetyenziswa i-salicylate 1-hydroxylase (S1H) okanye ngendlela ye-gentisate kusetyenziswa i-salicylate 5-hydroxylase (S5H) (Umfanekiso 3). Ekubeni i-salicylic acid iphakathi kakhulu kwi-naphthalene metabolism (indlela ephezulu), amanyathelo ukusuka kwi-salicylic acid ukuya kwi-TCA intermediate adla ngokubizwa ngokuba yindlela esezantsi, kwaye ii-genes zihlelwe zibe yi-operon enye. Kuqhelekile ukubona ukuba ii-genes ezikwi-operon (nah) kunye ne-operon (sal) zilawulwa zizinto eziqhelekileyo zokulawula; umzekelo, i-NahR kunye ne-salicylic acid zisebenza njengee-inducers, ezivumela zombini ii-operon ukuba zixutywe ngokupheleleyo ne-naphthalene (Phale et al., 2019, 2020).
Ukongeza, i-catechol ixutywa nge-cyclically ibe yi-2-hydroxymuconate semialdehyde ngendlela ye-meta yi-catechol 2,3-dioxygenase (C23DO) (Yen et al., 1988) kwaye ixutywa nge-hydrolyzed yi-2-hydroxymuconate semialdehyde hydrolase ukuze yenze i-2-hydroxypent-2,4-dienoic acid. I-2-hydroxypent-2,4-dienoate emva koko iguqulwa ibe yi-pyruvate kunye ne-acetaldehyde yi-hydratase (2-oxopent-4-enoate hydratase) kunye ne-aldolase (4-hydroxy-2-oxopentanoate aldolase) ize ingene kwindlela yekhabhoni ephakathi (Umfanekiso 3). Okanye, i-catechol ixutywa nge-cyclically ibe yi-cis,cis-muconate ngendlela ye-ortho yi-catechol 1,2-oxygenase (C12DO). I-Muconate cycloisomerase, i-muconolactone isomerase, kunye ne-β-ketoadipate-nollactone hydrolase ziguqula i-cis, cis-muconate ibe yi-3-oxoadipate, engena kwindlela ephakathi yekhabhoni nge-succinyl-CoA kunye ne-acetyl-CoA (Nozaki et al., 1968) (Umfanekiso 3).
Kwindlela ye-gentisate (2,5-dihydroxybenzoate), indandatho ye-aromatic iyaqhekeka yi-gentisate 1,2-dioxygenase (GDO) ukuze yenze i-maleylpyruvate. Le mveliso inokutsalwa ngqo kwi-pyruvate kunye ne-malate, okanye ingatsalwa i-isomerized ukwenza i-fumarylpyruvate, enokuthi emva koko itsalwe kwi-pyruvate kunye ne-fumarate (Larkin and Day, 1986). Ukukhethwa kwendlela eyahlukileyo kuye kwabonwa kwiibhaktheriya ze-Gram-negative kunye ne-Gram-positive kumanqanaba e-biochemical kunye ne-genetic (Morawski et al., 1997; Whyte et al., 1997). Iibhaktheriya ze-Gram-negative (Pseudomonas) zikhetha ukusebenzisa i-salicylic acid, eyisishukumisi se-naphthalene metabolism, eyi-decarboxylating it to catechol isebenzisa i-salicylate 1-hydroxylase (Gibson and Subramanian, 1984). Kwelinye icala, kwibhaktheriya eneGram-positive (Rhodococcus), i-salicylate 5-hydroxylase iguqula i-salicylic acid ibe yi-gentisic acid, ngelixa i-salicylic acid ingenampembelelo inductive kwi-transcription ye-naphthalene genes (Grund et al., 1992) (Umfanekiso 3).
Kuye kwaxelwa ukuba iintlobo ezifana nePseudomonas CSV86, Oceanobacterium NCE312, Marinhomonas naphthotrophicus, Sphingomonas paucimobilis 2322, Vibrio cyclotrophus, Pseudomonas fluorescens LP6a, Pseudomonas kunye neMycobacterium species zinokuyonakalisa i-monomethylnaphthalene okanye i-dimethylnaphthalene (Dean-Raymond kunye noBartha, 1975; Cane kunye noWilliams, 1982; Mahajan et al., 1994; Dutta et al., 1998; Hedlund et al., 1999). Phakathi kwazo, indlela yokubola kwe-1-methylnaphthalene kunye ne-2-methylnaphthalene yePseudomonas sp. CSV86 ifundwe ngokucacileyo kumanqanaba e-biochemical kunye ne-enzymatic (Mahajan et al., 1994). I-1-Methylnaphthalene ixutywa ngeendlela ezimbini. Okokuqala, iringi enuka kamnandi i-hydroxylated (iringi engatshintshwanga ye-methylnaphthalene) ukuze yenze i-cis-1,2-dihydroxy-1,2-dihydro-8-methylnaphthalene, ephinda i-oxidized ibe yi-methyl salicylate kunye ne-methylcatechol, ize ingene kwindlela ephakathi yekhabhoni emva kokuqhekeka kweringi (Umfanekiso 3). Le ndlela ibizwa ngokuba "yindlela yomthombo wekhabhoni". Kwindlela yesibini "yokususa ubuthi", iqela le-methyl linokuthi li-hydroxylated yi-NDO ukuze lenze i-1-hydroxymethylnaphthalene, ephinda i-oxidized ibe yi-1-naphthoic acid kwaye ikhutshwe kwindawo yokukhulisa njengemveliso engapheliyo. Izifundo zibonise ukuba uhlobo lwe-CSV86 alukwazi ukukhula kwi-1- kunye ne-2-naphthoic acid njengomthombo wekhabhoni kunye namandla, okuqinisekisa indlela yayo yokususa ubuthi (Mahajan et al., 1994; Basu et al., 2003). Kwi-2-methylnaphthalene, iqela le-methyl lidlula kwi-hydroxylation yi-hydroxylase ukuze lenze i-2-hydroxymethylnaphthalene. Ukongeza, iringi engatshintshiyo yeringi ye-naphthalene idlula kwi-ring hydroxylation ukuze yenze i-dihydrodiol, efakwa kwi-4-hydroxymethylcatechol kuthotho lwee-enzyme-catalyzed reactions kwaye ingena kwindlela ephakathi yekhabhoni ngendlela ye-meta-ring cleavage. Ngokufanayo, i-S. paucimobilis 2322 ibikwe ukuba isebenzisa i-NDO kwi-hydroxylate 2-methylnaphthalene, efakwa kwi-oxidized ukuze yenze i-methyl salicylate kunye ne-methylcatechol (Dutta et al., 1998).
Ii-asidi zeNaphthoic (ezifakwe endaweni yazo/ezingafakwanga endaweni yazo) ziimveliso eziphuma kwi-detoxification/biotransformation ezenziwe ngexesha lokudilizwa kwe-methylnaphthalene, i-phenanthrene kunye ne-anthracene kwaye zikhutshwe kwindawo yokulima echithwe. Kuye kwaxelwa ukuba umhlaba ohlukanisa iStenotrophomonas maltophilia CSV89 unako ukunyibilikisa i-1-naphthoic acid njengomthombo wekhabhoni (Phale et al., 1995). I-metabolism iqala nge-dihydroxylation yeringi enuka kamnandi ukuze yenze i-1,2-dihydroxy-8-carboxynaphthalene. I-diol ephumayo i-oxidized ibe yi-catechol nge-2-hydroxy-3-carboxybenzylidenepyruvate, i-3-formylsalicylic acid, i-2-hydroxyisophthalic acid kunye ne-salicylic acid kwaye ingena kwindlela ephakathi yekhabhoni ngendlela ye-meta-ring cleavage (Umfanekiso 3).
I-Carbaryl sisibulali-zinambuzane esibizwa ngokuba yi-naphthyl carbamate. Ukusukela kwiNguquko yeGreen eIndiya ngeminyaka yoo-1970, ukusetyenziswa kwezichumisi zeekhemikhali kunye nezibulali-zinambuzane kukhokelele ekwandeni kokukhutshwa kwe-polycyclic aromatic hydrocarbon (PAH) kwimithombo yezolimo engekho kwindawo (Pingali, 2012; Duttagupta et al., 2020). I-55% eqikelelweyo (iihektare ezingama-85,722,000) yomhlaba wonke wezityalo eIndiya iphathwa ngezibulali-zinambuzane zeekhemikhali. Kwiminyaka emihlanu edlulileyo (2015–2020), icandelo lezolimo laseIndiya lisebenzise umyinge weetoni ezingama-55,000 ukuya kuma-60,000 zeezinambuzane ngonyaka (iSebe leeNtsebenziswano kunye neNtlalontle yabaLimi, uMphathiswa wezoLimo, uRhulumente waseIndiya, ngo-Agasti 2020). Kwiindawo ezisemantla nasembindini weGangetic (amazwe anenani eliphezulu labantu kunye nobuninzi babemi), ukusetyenziswa kwezibulali-zinambuzane kwizityalo kuxhaphakile, kwaye izibulali-zinambuzane zixhaphakile. I-Carbaryl (1-naphthyl-N-methylcarbamate) sisibulali-zinambuzane se-carbamate esinobubanzi, esinobuthi obuphakathi ukuya kobuphezulu esisetyenziswa kwezolimo zaseIndiya ngesantya esiphakathi seetoni ezili-100–110. Ihlala ithengiswa phantsi kwegama lorhwebo elithi Sevin kwaye isetyenziselwa ukulawula izinambuzane (ii-aphids, iimbovane zomlilo, iintakumba, iincukuthu, izigcawu kunye nezinye izinambuzane ezininzi zangaphandle) ezichaphazela iintlobo ngeentlobo zezityalo (umbona, iimbotyi zesoya, umqhaphu, iziqhamo kunye nemifuno). Ezinye iintsholongwane ezifana nePseudomonas (NCIB 12042, 12043, C4, C5, C6, C7, Pseudomonas putida XWY-1), Rhodococcus (NCIB 12038), Sphingobacterium spp. (CF06), Burkholderia (C3), Micrococcus kunye neArthrobacter nazo zingasetyenziselwa ukulawula ezinye izinambuzane. Kuye kwaxelwa ukuba i-RC100 inokonakalisa i-carbaryl (uLarkin noDay, 1986; uChapalamadugu noChaudhry, 1991; uHayatsu et al., 1999; uSwetha noPhale, 2005; uTrivedi et al., 2017). Indlela yokubola kwe-carbaryl ifundwe ngokubanzi kumanqanaba e-biochemical, enzymatic kunye ne-genetic kwi-solid solid ye-Pseudomonas sp. Strains C4, C5 kunye ne-C6 (uSwetha noPhale, 2005; uTrivedi et al., 2016) (Umzobo 3). Indlela ye-metabolic iqala nge-hydrolysis ye-ester bond yi-carbaryl hydrolase (CH) ukwenza i-1-naphthol, i-methylamine kunye ne-carbon dioxide. Emva koko i-1-naphthol iguqulwa ibe yi-1,2-dihydroxynaphthalene yi-1-naphthol hydroxylase (1-NH), ephinda ixutywe ngendlela ephakathi yekhabhoni nge-salicylate kunye ne-gentisate. Ezinye iibhaktheriya ezibola i-carbaryl ziye zaxelwa ukuba ziyayiguqula ibe yi-salicylic acid ngokuqhekeka kweringi ye-catechol ortho (Larkin kunye noDay, 1986; Chapalamadugu kunye noChaudhry, 1991). Okuphawulekayo kukuba, iibhaktheriya ezibola i-naphthalene ikakhulu ziguqula i-salicylic acid nge-catechol, ngelixa iibhaktheriya ezibola i-carbaryl zikhetha ukuguqula i-salicylic acid ngendlela ye-gentisate.
I-Naphthalenesulfonic acid/disulfonic acid kunye ne-naphthylaminesulfonic acid derivatives zingasetyenziswa njengezinto eziphakathi ekuvelisweni kweedayi ze-azo, ii-wetting agents, ii-dispersants, njl. Nangona ezi compounds zinobuthi obuphantsi ebantwini, uvavanyo lwe-cytotoxicity lubonise ukuba ziyingozi kwiintlanzi, i-daphnia kunye ne-algae (Greim et al., 1994). Abameli be-genus Pseudomonas (iintlobo ze-A3, C22) baxelwe ukuba baqala i-metabolism nge-hydroxylation ephindwe kabini yeringi ye-aromatic equlethe iqela le-sulfonic acid ukwenza i-dihydrodiol, eguqulwa ngakumbi kwi-1,2-dihydroxynaphthalene ngokuqhekeka kweqela le-sulfite (Brilon et al., 1981). I-1,2-dihydroxynaphthalene ephumayo i-catabolized ngendlela ye-classical naphthalene, oko kukuthi, indlela ye-catechol okanye ye-gentisate (Umfanekiso 4). Kuye kwaboniswa ukuba i-aminonaphthalenesulfonic acid kunye ne-hydroxynaphthalenesulfonic acid zinokonakala ngokupheleleyo yi-mixed bacterial consortia eneendlela ze-catabolic ezongezelelweyo (Nortemann et al., 1986). Kuye kwaboniswa ukuba ilungu elinye le-consortium lisusa i-aminonaphthalenesulfonic acid okanye i-hydroxynaphthalenesulfonic acid nge-1,2-dioxygenation, ngelixa i-aminosalicylate okanye i-hydroxysalicylate ikhutshwa kwindawo yokukhulisa njenge-metabolite engapheliyo kwaye emva koko ithathwa ngamanye amalungu e-consortium. I-Naphthalenedisulfonic acid i-polar kodwa ayiboli kakuhle kwaye ngenxa yoko inokusetyenziswa ngeendlela ezahlukeneyo. I-desulfurization yokuqala yenzeka ngexesha le-regioselective dihydroxylation ye-aromatic ring kunye neqela le-sulfonic acid; i-desulfurization yesibini yenzeka ngexesha le-hydroxylation ye-5-sulfosalicylic acid yi-salicylic acid 5-hydroxylase ukuze yenze i-gentisic acid, engena kwindlela ephakathi yekhabhoni (Brilon et al., 1981) (Umfanekiso 4). Ii-enzymes ezinoxanduva lokudilizwa kwe-naphthalene nazo zinoxanduva lwe-naphthalene sulfonate metabolism (Brilon et al., 1981; Keck et al., 2006).
Umfanekiso 4. Iindlela zemetaboliki zokuwohloka kwe-naphthalene sulfonate. Amanani angaphakathi kwizangqa amele ii-enzymes ezinoxanduva lwemetabolism ye-naphthyl sulfonate, ezifanayo/ezifana nee-enzymes ezichazwe kuMfanekiso 3.
Ii-PAH eziphantsi zobunzima beemolekyuli (ii-LMW-PAH) ziyancitshiswa, azinamanzi kwaye azinyibiliki kakuhle, ngoko ke azichaphazeleki kukuqhekeka/ukubola kwendalo. Nangona kunjalo, ii-microorganisms ze-aerobic ziyakwazi ukuyinyibilikisa ngokufunxa ioksijini yemolekyuli (O2). Ezi enzymes ikakhulu ziphantsi kodidi lwee-oxidoreductases kwaye zinokwenza iimpendulo ezahlukeneyo ezifana ne-aromatic ring hydroxylation (i-mono- okanye i-dihydroxylation), i-dehydrogenation kunye ne-aromatic ring cleavage. Iimveliso ezifunyenwe kwezi mpendulo zikwimeko ephezulu ye-oxidation kwaye zixutywa lula ngendlela ye-carbon ephakathi (uPhale et al., 2020). Ii-enzymes ezikwindlela yokubola ziye zaxelwa ukuba azinakushukunyiswa. Umsebenzi wezi enzymes uphantsi kakhulu okanye awubonakali xa iiseli zikhuliswe kwimithombo elula yekhabhoni efana neglucose okanye ii-organic acids. Itheyibhile 3 ishwankathela ii-enzymes ezahlukeneyo (ii-oxygenases, ii-hydrolases, ii-dehydrogenases, ii-oxidases, njl.njl.) ezibandakanyeka kwi-metabolism ye-naphthalene kunye nezinto eziphuma kuyo.
Itheyibhile 3. Iimpawu zebhayoloji zee-enzymes ezibangela ukuwohloka kwe-naphthalene kunye nezinto eziphuma kuyo.
Izifundo zeRadioisotope (18O2) zibonise ukuba ukufakwa kwe-molecular O2 kwizangqa ze-aromatic yi-oxygenases yeyona nyathelo libalulekileyo ekuvuseleleni ukubola ngakumbi kwe-compound (Hayaishi et al., 1955; Mason et al., 1955). Ukufakwa kwe-atom enye ye-oxygen (O) kwi-molecule oxygen (O2) kwi-substrate kuqaliswa yi-endogenous okanye i-exogenous monooxygenases (ekwabizwa ngokuba yi-hydroxylases). Enye i-atom ye-oxygen incitshiswa ibe ngamanzi. Ii-exogenous monooxygenases zinciphisa i-flavin nge-NADH okanye i-NADPH, ngelixa kwi-endomonooxygenases i-flavin incitshiswa yi-substrate. Indawo ye-hydroxylation ibangela ukwahluka ekwakhiweni kwemveliso. Umzekelo, i-salicylate 1-hydroxylase hydroxylates salicylic acid kwindawo ye-C1, yenza i-catechol. Kwelinye icala, i-multicomponent salicylate 5-hydroxylase (equlethe i-reductase, i-ferredoxin, kunye ne-oxygenase subunits) i-hydroxylates i-salicylic acid kwindawo ye-C5, yenze i-gentisic acid (Yamamoto et al., 1965).
Ii-Dioxygenases zifaka ii-athomu ezimbini ze-O2 kwi-substrate. Ngokuxhomekeke kwiimveliso ezenziweyo, zahlulwe zibe zii-ring hydroxylating dioxygenases kunye nee-ring cleaving dioxygenases. Ii-ring hydroxylating dioxygenases ziguqula ii-aromatic substrates zibe yi-cis-dihydrodiols (umz., i-naphthalene) kwaye zixhaphake kakhulu kwiibhaktheriya. Ukuza kuthi ga ngoku, kubonisiwe ukuba izinto eziphilayo eziqulethe ii-ring hydroxylating dioxygenases ziyakwazi ukukhula kwimithombo eyahlukeneyo ye-aromatic carbon, kwaye ezi enzymes zihlelwe njenge-NDO (naphthalene), i-toluene dioxygenase (TDO, toluene), kunye ne-biphenyl dioxygenase (BPDO, biphenyl). Zombini i-NDO kunye ne-BPDO zinokuvuselela i-double oxidation kunye ne-side chain hydroxylation yee-hydrocarbons ezahlukeneyo ze-polycyclic aromatic (i-toluene, i-nitrotoluene, i-xylene, i-ethylbenzene, i-naphthalene, i-biphenyl, i-fluorene, i-indole, i-methylnaphthalene, i-naphthalenesulfonate, i-phenanthrene, i-anthracene, i-acetophenone, njl.njl.) (UBoyd kunye noSheldrake, 1998; UPhale et al., 2020). I-NDO yinkqubo ye-multicomponent equlathe i-oxidoreductase, i-ferredoxin, kunye ne-active site-containing oxygenase component (UGibson kunye noSubramanian, 1984; UResnick et al., 1996). Iyunithi ye-catalytic ye-NDO ine-subunit enkulu ye-α kunye ne-subunit encinci ye-β ehlelwe kwi-configuration ye-α3β3. I-NDO ikwintsapho enkulu yee-oxygenases kwaye i-α-subunit yayo iqulethe indawo yeRieske [2Fe-2S] kunye ne-mononuclear non-heme iron, emisela ubunyani be-substrate ye-NDO (Parales et al., 1998). Ngokwesiqhelo, kumjikelo omnye we-catalytic, ii-electron ezimbini ezivela ekunciphiseni i-pyridine nucleotide zidluliselwa kwi-Fe(II) ion kwindawo esebenzayo nge-reductase, i-ferredoxin kunye ne-Rieske site. Ii-reducing equivalents zivuselela i-molecule oxygen, nto leyo eyimfuneko ye-substrate dihydroxylation (Ferraro et al., 2005). Ukuza kuthi ga ngoku, zimbalwa ii-NDO ezicociweyo kwaye zachazwa ngokweenkcukacha kwiintlobo ezahlukeneyo kwaye ulawulo lwe-genetic lweendlela ezibandakanyeka ekuwohlokeni kwe-naphthalene luye lwafundwa ngokweenkcukacha (Resnick et al., 1996; Parales et al., 1998; Karlsson et al., 2003). Ii-diooxygenase eziqhekeza indandatho (ii-enzymes ze-endo- okanye ze-ortho-ring-cleaving kunye nee-enzymes ze-exodiol- okanye ze-meta-ring-cleaving) zisebenza kwiikhompawundi ze-aromatic ezifakwe i-hydroxylated. Umzekelo, i-ortho-ring-cleaving dioxygenase yi-catechol-1,2-dioxygenase, ngelixa i-meta-ring-cleaving dioxygenase yi-catechol-2,3-dioxygenase (Kojima et al., 1961; Nozaki et al., 1968). Ukongeza kwii-oxygenase ezahlukeneyo, kukwakho nee-dehydrogenase ezahlukeneyo ezinoxanduva lokunciphisa i-hydrogenation yee-aromatic dihydrodiols, ii-alcohols kunye nee-aldehydes kunye nokusebenzisa i-NAD+/NADP+ njengee-electron acceptors, ezizezinye zee-enzymes ezibalulekileyo ezibandakanyeka kwi-metabolism (Gibson and Subramanian, 1984; Shaw and Harayama, 1990; Fahle et al., 2020).
Iienzyme ezifana neehydrolases (ii-esterases, ii-amidases) ziluhlobo lwesibini olubalulekileyo lwee-enzymes ezisebenzisa amanzi ukwahlula ii-covalent bonds kwaye zibonise ubunyani be-substrate ebanzi. I-Carbaryl hydrolase kunye nezinye ii-hydrolases zithathwa njengeziqulatho ze-periplasm (i-transmembrane) kumalungu eebhaktheriya ze-Gram-negative (uKamini et al., 2018). I-Carbaryl ine-amide kunye ne-ester linkage; ngoko ke, inokutsalwa yi-esterase okanye i-amidase ukuze yenze i-1-naphthol. I-Carbaryl kwi-Rhizobium rhizobium strain AC10023 kunye ne-Arthrobacter strain RC100 zibikwe ukuba zisebenza njenge-esterase kunye ne-amidase, ngokwahlukeneyo. I-Carbaryl kwi-Arthrobacter strain RC100 ikwasebenza njenge-amidase. I-RC100 ibonakalisiwe ukuba i-hydrolyze izibulali-zinambuzane ezine zeklasi ye-N-methylcarbamate ezifana ne-carbaryl, i-methomyl, i-mefenamic acid kunye ne-XMC (Hayaatsu et al., 2001). Kuxelwe ukuba i-CH kwi-Pseudomonas sp. C5pp inokusebenza kwi-carbaryl (umsebenzi we-100%) kunye ne-1-naphthyl acetate (umsebenzi we-36%), kodwa hayi kwi-1-naphthylacetamide, nto leyo ebonisa ukuba yi-esterase (Trivedi et al., 2016).
Izifundo zebhayoloji, iipateni zokulawula i-enzyme, kunye nohlalutyo lwe-genetic zibonise ukuba ii-genes zokuchithwa kwe-naphthalene ziquka iiyunithi ezimbini zokulawula ezinokuthi zisetyenziswe okanye "ii-operon": i-nah ("indlela ephezulu", eguqula i-naphthalene ibe yi-salicylic acid) kunye ne-sal ("indlela ephantsi", eguqula i-salicylic acid ibe yindlela ephakathi yekhabhoni nge-catechol). I-Salicylic acid kunye nee-analogues zayo zinokusebenza njengee-inducers (Shamsuzzaman kunye neBarnsley, 1974). Ukuba kukho i-glucose okanye ii-organic acids, i-operon iyacinezelwa. Umfanekiso 5 ubonisa ulungelelwaniso olupheleleyo lwe-genetic lokuchithwa kwe-naphthalene (kwimo ye-operon). Iindidi ezahlukeneyo/iifom ze-nah gene (ndo/pah/dox) zichazwe kwaye zifunyenwe zine-homology ephezulu (90%) phakathi kwazo zonke iintlobo ze-Pseudomonas (Abbasian et al., 2016). Ii-genes ze-naphthalene upstream pathway zihlala zicwangciswe ngokulandelelana njengoko kubonisiwe kuMfanekiso 5A. Enye i-gene, i-nahQ, nayo ibikwa ukuba ibandakanyeka kwi-metabolism ye-naphthalene kwaye yayihlala iphakathi kwe-nahC kunye ne-nahE, kodwa umsebenzi wayo wokwenyani usaza kucaciswa. Ngokufanayo, i-gene ye-nahY, enoxanduva lwe-chemotaxis ebuthathaka kwi-naphthalene, ifunyenwe kwisiphelo esikude se-nah operon kwamanye amalungu. Kwi-Ralstonia sp., i-gene ye-U2 ebhala i-glutathione S-transferase (gsh) ifunyenwe iphakathi kwe-nahAa kunye ne-nahAb kodwa ayizange ichaphazele iimpawu zokusetyenziswa kwe-naphthalene (Zylstra et al., 1997).
Umfanekiso 5. Ulungelelwaniso lwemfuza kunye nokwahluka okubonwayo ngexesha lokuwohloka kwe-naphthalene phakathi kweentlobo zebhaktheriya; (A) Indlela ephezulu ye-naphthalene, imetabolism ye-naphthalene ibe yi-salicylic acid; (B) Indlela ephantsi ye-naphthalene, i-salicylic acid nge-catechol ukuya kwindlela ephakathi yekhabhoni; (C) i-salicylic acid nge-gentisate ukuya kwindlela ephakathi yekhabhoni.
"Indlela esezantsi" (i-sal operon) idla ngokuba ne-nahGTHINLMOKJ kwaye iguqula i-salicylate ibe yi-pyruvate kunye ne-acetaldehyde ngendlela ye-catechol metaring cleavage. I-nahG gene (efaka i-salicylate hydroxylase) ifunyenwe igcinwe kwisiphelo esikufutshane se-operon (Umzobo 5B). Xa kuthelekiswa nezinye iintlobo ze-naphthalene-degrading, kwi-P. putida CSV86 i-nah kunye ne-sal operon zidibene kwaye zihlobene kakhulu (malunga ne-7.5 kb). Kwezinye iibhaktheriya ze-Gram-negative, ezifana neRalstonia sp. U2, iPolaromonas naphthalenivorans CJ2, kunye ne-P. putida AK5, i-naphthalene ixutywa njenge-metabolite yekhabhoni ephakathi ngendlela ye-gentisate (ngendlela ye-sgp/nag operon). Ikhasethi ye-gene idla ngokumelwa kwimo ye-nagAaGHabAcAdBFCQEDJI, apho i-nagR (efaka ikhowudi kumlawuli wohlobo lwe-LysR) ikwisiphelo esiphezulu (Umfanekiso 5C).
I-Carbaryl ingena kumjikelo wekhabhoni ephakathi ngokusebenzisa imetabolism ye-1-naphthol, i-1,2-dihydroxynaphthalene, i-salicylic acid, kunye ne-gentisic acid (Umfanekiso 3). Ngokusekelwe kwizifundo ze-genetic kunye ne-metabolic, kuye kwacetyiswa ukuba le ndlela yahlulwe ibe "phezulu" (ukuguqulwa kwe-carbaryl ibe yi-salicylic acid), "phakathi" (ukuguqulwa kwe-salicylic acid ibe yi-gentisic acid), kunye "nokwehla" (ukuguqulwa kwe-gentisic acid ibe yi-central carbon pathway intermediates) (Singh et al., 2013). Uhlalutyo lwe-genomic lwe-C5pp (supercontig A, 76.3 kb) lutyhile ukuba i-mcbACBDEF gene ibandakanyeka ekuguqulweni kwe-carbaryl ibe yi-salicylic acid, ilandelwe yi-mcbIJKL ekuguqulweni kwe-salicylic acid ibe yi-gentisic acid, kunye ne-mcbOQP ekuguqulweni kwe-gentisic acid ibe yi-central carbon intermediates (fumarate kunye ne-pyruvate, Trivedi et al., 2016) (Umfanekiso 6).
Kuye kwaxelwa ukuba ii-enzymes ezibandakanyeka ekonakaleni kwee-hydrocarbons ezinuka kamnandi (kubandakanya i-naphthalene kunye ne-salicylic acid) zinokubangelwa ziikhompawundi ezifanelekileyo kwaye zithintelwe yimithombo elula yekhabhoni efana ne-glucose okanye ii-organic acids (Shingler, 2003; Phale et al., 2019, 2020). Phakathi kweendlela ezahlukeneyo ze-metabolic ze-naphthalene kunye ne-derivatives yayo, iimpawu zolawulo ze-naphthalene kunye ne-carbaryl ziye zafundwa ukuya kuthi ga kwinqanaba elithile. Kwi-naphthalene, ii-genes kuzo zombini iindlela eziphezulu nezisezantsi zilawulwa yi-NahR, i-LysR-type trans-acting positive regulator. Iyimfuneko ekungenisweni kwe-nah gene yi-salicylic acid kunye nokubonakaliswa kwayo okuphezulu okulandelayo (Yen kunye neGunsalus, 1982). Ngaphezu koko, izifundo zibonise ukuba i-integrative host factor (IHF) kunye ne-XylR (sigma 54-dependent transcriptional regulator) nazo zibalulekile ekusebenzeni kwe-transcriptional yee-genes kwi-naphthalene metabolism (Ramos et al., 1997). Izifundo zibonise ukuba ii-enzymes zendlela yokuvula i-catechol meta-ring, oko kukuthi i-catechol 2,3-dioxygenase, zenziwa xa kukho i-naphthalene kunye/okanye i-salicylic acid (Basu et al., 2006). Izifundo zibonise ukuba ii-enzymes zendlela yokuvula i-catechol ortho-ring, oko kukuthi i-catechol 1,2-dioxygenase, zenziwa xa kukho i-benzoic acid kunye ne-cis,cis-muconate (Parsek et al., 1994; Tover et al., 2001).
Kwi-strain C5pp, iijini ezintlanu, i-mcbG, i-mcbH, i-mcbN, i-mcbR kunye ne-mcbS, zibhala ii-control regulators ezikusapho lweLysR/TetR lwabalawuli be-transcriptional abanoxanduva lokulawula ukubola kwe-carbaryl. I-homologous gene mcbG ifunyenwe inxulumene kakhulu ne-LysR-type regulator PhnS (58% amino acid identity) ebandakanyeka kwi-phenanthrene metabolism kwiBurkholderia RP00725 (Trivedi et al., 2016). I-mcbH gene ifunyenwe ibandakanyeka kwindlela ephakathi (ukuguqulwa kwe-salicylic acid ibe yi-gentisic acid) kwaye ikwi-LysR-type transcriptional regulator NagR/DntR/NahR kwiPseudomonas naseBurkholderia. Amalungu olu sapho axelwe ukuba ayayiqonda i-salicylic acid njengemolekyuli ethile ye-effector yokungenisa iijini ze-degradation. Kwelinye icala, iijini ezintathu, i-mcbN, i-mcbR kunye ne-mcbS, ezizezolawulo lwe-LysR kunye ne-TetR type transcriptional, zichongiwe kwindlela esezantsi (i-gentisate-central carbon pathway metabolites).
Kwiiprokaryotes, iinkqubo zokudlulisa iijini ezithe tyaba (ukufunyanwa, ukutshintshiselana, okanye ukudluliselwa) ngeplasmids, iitransposons, iiprophages, ii-genomic islands, kunye nezinto ezidityanisiweyo (ICE) zezona zinto ziphambili zeplastiki kwi-genomes zebhaktiriya, nto leyo ekhokelela ekufumaneni okanye ekulahlekelweni kwemisebenzi/iimpawu ezithile. Ivumela iibhaktiriya ukuba zilungelelane ngokukhawuleza kwiimeko ezahlukeneyo zendalo, zibonelela ngeenzuzo ezinokubakho ze-metabolic kwi-host, ezifana nokudilizwa kwee-compounds ze-aromatic. Utshintsho lwe-metabolic ludla ngokufezekiswa ngokulungiswa kakuhle kwee-operons zokudilizwa, iindlela zazo zokulawula, kunye ne-enzyme specificities, ezenza kube lula ukudilizwa koluhlu olubanzi lwee-compounds ze-aromatic (Nojiri et al., 2004; Phale et al., 2019, 2020). Ii-cassette ze-gene zokudilizwa kwe-naphthalene zifunyenwe zifumaneka kwiindidi ezahlukeneyo zezinto ezihambayo ezifana ne-plasmids (edityanisiweyo nengadityanisiweyo), ii-transposons, ii-genomes, ii-ICEs, kunye nokudibanisa iintlobo ezahlukeneyo zebhaktiriya (Umfanekiso 5). Kwi-Pseudomonas G7, ii-nah kunye nee-sal operon ze-plasmid NAH7 zibhalwe ngendlela efanayo kwaye ziyinxalenye ye-transposon enesiphene efuna i-transposase Tn4653 ukuze ikwazi ukuhambahamba (Sota et al., 2006). Kwi-Pseudomonas strain NCIB9816-4, i-gene ifunyenwe kwi-conjugative plasmid pDTG1 njengee-operon ezimbini (malunga ne-15 kb ngaphandle) ezibhalwe kwicala elichaseneyo (Dennis kunye noZylstra, 2004). Kwi-Pseudomonas putida strain AK5, i-non-conjugative plasmid pAK5 ibhala i-enzyme enoxanduva lokudilizwa kwe-naphthalene ngendlela ye-gentisate (Izmalkova et al., 2013). Kwi-Pseudomonas strain PMD-1, i-nah operon ikwi-chromosome, ngelixa i-sal operon ikwi-conjugative plasmid pMWD-1 (Zuniga et al., 1981). Nangona kunjalo, kwi-Pseudomonas stutzeri AN10, zonke ii-naphthalene degradation genes (nah kunye ne-sal operon) zikwi-chromosome kwaye mhlawumbi zifunyanwa nge-transposition, recombination, kunye ne-rearrangement events (Bosch et al., 2000). Kwi-Pseudomonas sp. CSV86, ii-nah kunye ne-sal operon zikwi-genome ngendlela ye-ICE (ICECSV86). Isakhiwo sikhuselwe yi-tRNAGly elandelwa kukuphindaphinda ngokuthe ngqo okubonisa iindawo zokuphinda-phinda/zokudibanisa (attR kunye ne-attL) kunye ne-integrase efana ne-phage efumaneka kuzo zombini iziphelo ze-tRNAGly, ngaloo ndlela ifana ngokwesakhiwo ne-ICEclc element (ICEclcB13 kwi-Pseudomonas knackmusii yokuchithwa kwe-chlorocatechol). Kuye kwaxelwa ukuba ii-genes kwi-ICE zinokudluliselwa ngokudibanisa nge-frequency yokudluliselwa ephantsi kakhulu (10-8), ngaloo ndlela zidlulisela iipropati zokuchithwa komgangatho kulowo ufumanayo (Basu kunye noPhale, 2008; Phale et al., 2019).
Uninzi lwezakhi zofuzo ezibangela ukubola kwe-carbaryl zifumaneka kwi-plasmids. I-Arthrobacter sp. RC100 iqulethe ii-plasmids ezintathu (pRC1, pRC2 kunye ne-pRC300) apho ii-plasmids ezimbini ezidityanisiweyo, i-pRC1 kunye ne-pRC2, zibhala ii-enzymes eziguqula i-carbaryl ibe yi-gentisate. Kwelinye icala, ii-enzymes ezibandakanyekayo ekuguqulweni kwe-gentisate kwi-metabolites ye-carbon ephakathi zifumaneka kwi-chromosome (Hayaatsu et al., 1999). Iibhaktheriya ze-genus Rhizobium. I-Strain AC100, esetyenziselwa ukuguqula i-carbaryl ibe yi-1-naphthol, iqulethe i-plasmid pAC200, ephethe i-cehA gene ebhala i-CH njengenxalenye ye-Tnceh transposon ejikelezwe zi-insertion element-like sequences (istA kunye ne-istB) (Hashimoto et al., 2002). Kwi-Sphingomonas strain CF06, i-carbaryl degradation gene kukholelwa ukuba ikhona kwiiplasmids ezintlanu: i-pCF01, i-pCF02, i-pCF03, i-pCF04, kunye ne-pCF05. I-DNA homology yezi plasmids iphezulu, nto leyo ebonisa ukuba kukho isiganeko sokuphindaphinda i-gene (Feng et al., 1997). Kwi-symbiont ye-carbaryl-degrading eyenziwe ziintlobo ezimbini ze-Pseudomonas, i-strain 50581 iqulethe i-conjugative plasmid pCD1 (50 kb) ebhala i-mcd carbaryl hydrolase gene, ngelixa i-conjugative plasmid kwi-strain 50552 ibhala i-enzyme ye-1-naphthol-degrading (Chapalamadugu kunye noChaudhry, 1991). Kwi-Achromobacter strain WM111, i-mcd furadan hydrolase gene ikwi-plasmid ye-100 kb (pPDL11). Le gene ibonakalisiwe ukuba ikhona kwiiplasmids ezahlukeneyo (100, 105, 115 okanye 124 kb) kwiibhaktheriya ezahlukeneyo ezivela kwiindawo ezahlukeneyo zejografi (Parekh et al., 1995). KwiPseudomonas sp. C5pp, zonke iigenes ezibangela ukubola kwe-carbaryl zikwi-genome ethatha i-76.3 kb yolandelelwano (Trivesi et al., 2016). Uhlalutyo lwe-genome (6.15 Mb) lubonise ubukho bee-MGEs ezingama-42 kunye nee-GEIs ezingama-36, apho ii-MGEs ezili-17 zazikwi-supercontig A (76.3 kb) enomxholo we-G+C ophakathi ongalinganiyo (54–60 mol%), nto leyo ebonisa ukuba kunokwenzeka ukuba kubekho iziganeko zokudluliselwa kwe-gene ethe tye (Trivesi et al., 2016). I-P. putida XWY-1 ibonisa ulungelelwaniso olufanayo lwee-genes ezibola i-carbaryl, kodwa ezi genes zikwi-plasmid (Zhu et al., 2019).
Ukongeza ekusebenzeni kakuhle kwe-metabolism kumanqanaba e-biochemical kunye ne-genomic, ii-microorganisms zikwabonisa ezinye iipropati okanye iimpendulo ezifana ne-chemotaxis, iipropati zokuguqulwa komphezulu weseli, ukwahlulahlula, ukusetyenziswa okukhethekileyo, ukuveliswa kwe-biosurfactant, njl.njl., ezizinceda ukuba zikwazi ukucola ngokufanelekileyo izinto ezingcolisayo kwiindawo ezingcolisiweyo (Umfanekiso 7).
Umfanekiso 7. Iindlela ezahlukeneyo zokuphendula iiseli zebhaktheriya eyonakalisayo ye-hydrocarbon efanelekileyo yokubola kwe-biodegradation yeekhompawundi zongcoliseko zangaphandle.
Iimpendulo ze-chemotactic zithathwa njengezinto ezibangela ukonakaliswa kwezinto eziphilayo ezingcolisa kakhulu kwiindawo eziphilayo ezingcolisekileyo. (2002) zibonise ukuba i-chemotaxis ye-Pseudomonas sp. G7 ukuya kwi-naphthalene yonyusa izinga lokuwohloka kwe-naphthalene kwiinkqubo zasemanzini. Uhlobo lwe-wild-type G7 lonakalise i-naphthalene ngokukhawuleza kakhulu kunohlobo lwe-chemotaxis olungenalo i-mutant. Iproteni ye-NahY (ii-amino acid ezingama-538 ezine-membrane topology) ifunyenwe idityaniswe ne-metacleavage pathway genes kwi-NAH7 plasmid, kwaye njenge-chemotaxis transducers, le proteni ibonakala isebenza njenge-chemoreceptor yokuwohloka kwe-naphthalene (Grimm kunye noHarwood 1997). Olunye uphando lukaHansel et al. (2009) lubonise ukuba iproteni yi-chemotactic, kodwa izinga layo lokuwohloka liphezulu. (2011) ubonise impendulo ye-chemotactic ye-Pseudomonas (P. putida) kwi-naphthalene yegesi, apho ukusasazeka kwesigaba segesi kubangele ukuhamba rhoqo kwe-naphthalene kwiiseli, nto leyo elawula impendulo ye-chemotactic yeeseli. Abaphandi basebenzise olu hlobo lokuziphatha kwe-chemotactic ukwenza ii-microbes eziya kuphucula izinga lokubola. Izifundo zibonise ukuba iindlela ze-chemosensory zilawula neminye imisebenzi yeseli efana nokwahlukana kweeseli, ukulawulwa komjikelo weseli, kunye nokwakheka kwe-biofilm, ngaloo ndlela zinceda ukulawula izinga lokubola. Nangona kunjalo, ukusebenzisa le propati (chemotaxis) ukuze kubola ngokufanelekileyo kuthintelwa ziingxaki ezininzi. Imiqobo ephambili yile: (a) ii-receptors ezahlukeneyo ze-paralogous ziyaziqonda iikhompawundi/ii-ligands ezifanayo; (b) ubukho bee-receptors ezizezinye, oko kukuthi, i-energy tropism; (c) umahluko obalulekileyo wolandelelwano kwiindawo zeemvakalelo zosapho olufanayo lwee-receptor; kunye (d) ukungabikho kolwazi kwiiproteni ze-sensor eziphambili zebhaktheriya (Ortega et al., 2017; Martin-Mora et al., 2018). Ngamanye amaxesha, ukubola kwe-biodegradation ye-aromatic hydrocarbons kuvelisa ii-metabolites/intermediates ezininzi, ezinokuba yi-chemotactic kwiqela elinye leebhaktheriya kodwa zinyanyeke kwezinye, nto leyo eyenze kube nzima ngakumbi inkqubo. Ukuze sichonge ukusebenzisana kwee-ligands (ii-aromatic hydrocarbons) kunye nee-chemical receptors, sakhe iiproteni ze-hybrid sensor (PcaY, McfR, kunye neNahY) ngokudibanisa i-sensor kunye ne-signaling domains zePseudomonas putida kunye ne-Escherichia coli, ezijolise kwii-receptors ze-aromatic acids, ii-TCA intermediates, kunye ne-naphthalene, ngokwahlukeneyo (Luu et al., 2019).
Phantsi kwempembelelo ye-naphthalene kunye nezinye ii-polycyclic aromatic hydrocarbons (ii-PAH), ulwakhiwo lwe-bacterial membrane kunye nokuthembeka kwee-microorganisms kutshintsha kakhulu. Izifundo zibonise ukuba i-naphthalene iphazamisana nokusebenzisana kwe-acyl chain ngokusebenzisa ukusebenzisana kwe-hydrophobic, ngaloo ndlela inyusa ukudumba kunye nokugeleza kwe-membrane (uSikkema et al., 1995). Ukumelana nale mpembelelo imbi, iibhaktheriya zilawula ukugeleza kwe-membrane ngokutshintsha umlinganiselo kunye nokwakheka kwe-fatty acid phakathi kwe-iso/anteiso branched-chain fatty acids kunye ne-isomerizing cis-unsaturated fatty acids kwi-trans-isomers ehambelanayo (uHeipieper kunye no-de Bont, 1994). Kwi-Pseudomonas stutzeri ekhuliswe kunyango lwe-naphthalene, umlinganiselo we-fatty acid ogcweleyo ukuya kwi-unsaturated unyuke ukusuka kwi-1.1 ukuya kwi-2.1, ngelixa kwi-Pseudomonas JS150 lo mlinganiselo unyuke ukusuka kwi-7.5 ukuya kwi-12.0 (uMrozik et al., 2004). Xa ikhuliswe kwi-naphthalene, iiseli ze-Achromobacter KAs 3-5 zibonise ukuhlanganiswa kweeseli ezijikeleze iikristale ze-naphthalene kunye nokwehla kwentlawulo yomphezulu weseli (ukusuka kwi--22.5 ukuya kwi--2.5 mV) ehamba kunye nokuxinana kwe-cytoplasmic kunye ne-vacuolization, okubonisa utshintsho kwisakhiwo seseli kunye neempawu zomphezulu weseli (Mohapatra et al., 2019). Nangona utshintsho lweseli/umphezulu lunxulunyaniswa ngokuthe ngqo nokufunxwa ngcono kwezinto ezingcolisayo ezinuka kamnandi, amaqhinga obunjineli be-bio awakalungiswa ngokupheleleyo. Ukuguqulwa kwemilo yeseli akukasetyenziswa rhoqo ukuphucula iinkqubo zebhayoloji (Volke kunye noNikel, 2018). Ukususwa kweejini ezichaphazela ukwahlukana kweseli kubangela utshintsho kwimo yeseli. Ukususwa kweejini ezichaphazela ukwahlukana kweseli kubangela utshintsho kwimo yeseli. Kwi-Bacillus subtilis, iprotheyini ye-septum yeseli i-SepF ibonakalisiwe ukuba ibandakanyeka ekwakhiweni kwe-septum kwaye iyimfuneko kumanyathelo alandelayo okwahlukana kweseli, kodwa ayisiyojini ebalulekileyo. Ukususwa kweejini ezifaka i-peptide glycan hydrolases kwiBacillus subtilis kubangele ukwanda kweeseli, ukwanda kwesantya sokukhula esithile, kunye nokuphuculwa kwamandla emveliso yee-enzyme (Cui et al., 2018).
Kucetyisiwe ukwahlulahlula indlela yokubola kwe-carbaryl ukuze kufezekiswe ukubola okusebenzayo kweentlobo zePseudomonas C5pp kunye ne-C7 (Kamini et al., 2018). Kucetyisiwe ukuba i-carbaryl ithuthwe iye kwindawo ye-periplasmic nge-external membrane septum kunye/okanye ngee-diffusible porins. I-CH yi-periplasmic enzyme ekhuthaza i-hydrolysis ye-carbaryl ukuya kwi-1-naphthol, ezinzileyo ngakumbi, ethanda ukungabi namanzi kwaye inetyhefu ngakumbi. I-CH ikwi-periplasm kwaye ine-affinity ephantsi ye-carbaryl, ngaloo ndlela ilawula ukwakheka kwe-1-naphthol, ngaloo ndlela ithintela ukuqokelelana kwayo kwiiseli kwaye inciphise ubuthi bayo kwiiseli (Kamini et al., 2018). I-1-naphthol ephumayo ithuthwa iye kwi-cytoplasm ngaphaya kwe-internal membrane ngokwahlulahlula kunye/okanye ukusasazwa, kwaye emva koko i-hydroxylated ibe yi-1,2-dihydroxynaphthalene yi-high-affinity enzyme 1NH ukuze iqhubeke ne-metabolism kwindlela ephakathi yekhabhoni.
Nangona iintsholongwane zinamandla emfuza kunye ne-metabolic okonakalisa imithombo yekhabhoni ye-xenobiotic, ulwakhiwo lwe-hierarchical lokusetyenziswa kwazo (oko kukuthi, ukusetyenziswa okukhethekileyo kwemithombo yekhabhoni elula kuneminye) ngumqobo omkhulu kwi-biodegradation. Ubukho kunye nokusetyenziswa kwemithombo yekhabhoni elula kunciphisa ii-genes ezifaka ii-enzymes ezitshabalalisa imithombo yekhabhoni eyinkimbinkimbi/engakhethwayo efana nee-PAH. Umzekelo ofundwe kakuhle kukuba xa i-glucose kunye ne-lactose zisondliwa kunye kwi-Escherichia coli, i-glucose isetyenziswa ngokufanelekileyo kune-lactose (Jacob and Monod, 1965). Kuye kwaxelwa ukuba ii-Pseudomonas zinciphisa iintlobo ngeentlobo zee-PAH kunye nee-xenobiotic compounds njengemithombo yekhabhoni. Ulawulo lokusetyenziswa kwemithombo yekhabhoni kwi-Pseudomonas zii-organic acids > glucose > ii-aromatic compounds (Hylemon and Phibbs, 1972; Collier et al., 1996). Nangona kunjalo, kukho umahluko. Okunomdla kukuba, i-Pseudomonas sp. I-CSV86 ibonisa isakhiwo esikhethekileyo esisebenzisa ngokukhethekileyo ii-hydrocarbons ezinuka kamnandi (i-benzoic acid, i-naphthalene, njl.njl.) endaweni ye-glucose kwaye idibanise ii-hydrocarbons ezinuka kamnandi kunye nee-organic acids (Basu et al., 2006). Kule bhaktiriya, ii-genes zokonakala kunye nokuthuthwa kwee-hydrocarbons ezinuka kamnandi azilawulwa nokuba kukho umthombo wesibini wekhabhoni njenge-glucose okanye ii-organic acids. Xa zikhuliswe kwi-glucose kunye ne-aromatic hydrocarbons medium, kwabonwa ukuba ii-genes zokuthutha i-glucose kunye ne-metabolism zazilawulwa, ii-hydrocarbons ezinuka kamnandi zasetyenziswa kwisigaba sokuqala se-log, kwaye i-glucose yasetyenziswa kwisigaba sesibini se-log (Basu et al., 2006; Choudhary et al., 2017). Kwelinye icala, ubukho bee-organic acids abuzange buchaphazele ukubonakaliswa kwe-aromatic hydrocarbon metabolism, ngoko ke le bhaktiriya kulindeleke ukuba ibe yingxaki efunekayo kwizifundo zokubola kwe-biodegradation (Phale et al., 2020).
Kuyaziwa ukuba i-hydrocarbon biotransformation inokubangela uxinzelelo lwe-oxidative kunye nokwanda kwee-enzymes ze-antioxidant kwii-microorganisms. Ukubola kwe-naphthalene okungasebenzi kakuhle kokubini kwiiseli zesigaba esingashukumiyo kunye nokuba kukho iikhompawundi ezinobuthi kukhokelela ekwakhiweni kweentlobo ze-oxygen ezisabelayo (ROS) (Kang et al. 2006). Ekubeni ii-enzymes ezibola i-naphthalene ziqulathe amaqela e-iron-sulfur, phantsi koxinzelelo lwe-oxidative, i-iron kwi-heme kunye neeproteni ze-iron-sulfur ziya kubola, nto leyo ekhokelela ekungasebenzini kweproteni. I-Ferredoxin-NADP+ reductase (Fpr), kunye ne-superoxide dismutase (SOD), ilawula impendulo ye-reversible redox phakathi kwe-NADP+/NADPH kunye neemolekyuli ezimbini ze-ferredoxin okanye i-flavodoxin, ngaloo ndlela isusa i-ROS kwaye ibuyisele iziko le-iron-sulfur phantsi koxinzelelo lwe-oxidative (Li et al. 2006). Kuye kwaxelwa ukuba zombini i-Fpr kunye ne-SodA (SOD) kwi-Pseudomonas zinokubangelwa luxinzelelo lwe-oxidative, kwaye ukwanda kwemisebenzi ye-SOD kunye ne-catalase kubonwe kwiintlobo ezine ze-Pseudomonas (O1, W1, As1, kunye ne-G1) ngexesha lokukhula phantsi kweemeko ezongezwe yi-naphthalene (Kang et al., 2006). Izifundo zibonise ukuba ukongezwa kwee-antioxidants ezifana ne-ascorbic acid okanye i-ferrous iron (Fe2+) kunokunyusa izinga lokukhula kwe-naphthalene. Xa i-Rhodococcus erythropolis ikhula kwi-naphthalene medium, ukuguqulelwa kwe-cytochrome P450 genes enxulumene noxinzelelo lwe-oxidative kuquka i-sodA (Fe/Mn superoxide dismutase), i-sodC (Cu/Zn superoxide dismutase), kunye ne-recA kwandisiwe (Sazykin et al., 2019). Uhlalutyo oluthelekisayo lweproteomic lweeseli zePseudomonas ezikhuliswe kwi-naphthalene lubonise ukuba ukwandiswa kweeproteni ezahlukeneyo ezinxulumene nempendulo yoxinzelelo lwe-oxidative yindlela yokujongana noxinzelelo (Herbst et al., 2013).
Kuye kwaxelwa ukuba ii-microorganisms zivelisa ii-biosurfactants phantsi kwesenzo semithombo yekhabhoni e-hydrophobic. Ezi surfactants ziikhompawundi ezisebenzayo kumphezulu we-amphiphilic ezinokwenza ii-aggregates kwiindawo ezinamanzi eoyile okanye amanzi omoya. Oku kukhuthaza ukunyibilika okungamampunge kwaye kwenza kube lula ukufunxwa kwee-hydrocarbons ezinuka kamnandi, nto leyo ekhokelela ekuboleni kakuhle kwezinto eziphilayo (Rahman et al., 2002). Ngenxa yezi mpawu, ii-biosurfactants zisetyenziswa kakhulu kumashishini ahlukeneyo. Ukongezwa kwee-surfactants zeekhemikhali okanye ii-biosurfactants kwiinkcubeko zebhaktheriya kunokunyusa ukusebenza kakuhle kunye nesantya sokudilika kwee-hydrocarbon. Phakathi kwee-biosurfactants, ii-rhamnolipids eziveliswa yiPseudomonas aeruginosa zifundwe kakhulu kwaye zachazwa (Hisatsuka et al., 1971; Rahman et al., 2002). Ukongeza, ezinye iintlobo ze-biosurfactants ziquka ii-lipopeptides (ii-mucins ezivela kwi-Pseudomonas fluorescens), i-emulsifier 378 (evela kwi-Pseudomonas fluorescens) (uRosenberg noRon, 1999), ii-lipids ze-trehalose disaccharide ezivela kwi-Rhodococcus (uRamdahl, 1985), i-lichenin evela kwi-Bacillus (uSaraswathy no-Hallberg, 2002), kunye ne-surfactant evela kwi-Bacillus subtilis (uSiegmund no-Wagner, 1991) kunye ne-Bacillus amyloliquefaciens (uZhi et al., 2017). Ezi surfactants zinamandla zibonakalisiwe ukuba zinciphisa uxinzelelo lomphezulu ukusuka kwi-72 dynes/cm ukuya ngaphantsi kwe-30 dynes/cm, okuvumela ukufunxwa okungcono kwe-hydrocarbon. Kuye kwaxelwa ukuba iPseudomonas, iBacillus, iRhodococcus, iBurkholderia kunye nezinye iintlobo zebhaktiriya zinokuvelisa ii-biosurfactants ezahlukeneyo ze-rhamnolipid kunye ne-glycolipid xa zikhuliswe kwi-naphthalene kunye ne-methylnaphthalene media (Kanga et al., 1997; Puntus et al., 2005). I-Pseudomonas maltophilia CSV89 inokuvelisa i-extracellular biosurfactant Biosur-Pm xa ikhuliswe kwiikhompawundi ze-aromatic ezifana ne-naphthoic acid (Phale et al., 1995). I-kinetics yokwakheka kwe-Biosur-Pm ibonise ukuba ukwenziwa kwayo yinkqubo exhomekeke ekukhuleni nasekukhuleni kwe-pH. Kufunyaniswe ukuba isixa se-Biosur-Pm esiveliswa ziiseli kwi-pH engathathi cala sasiphezulu kuneso sikwi-pH 8.5. Iiseli ezikhuliswe kwi-pH 8.5 zazingenamanzi amaninzi kwaye zazinobuhlobo obuphezulu kwiikhompawundi ze-aromatic kunye ne-aliphatic kuneeseli ezikhuliswe kwi-pH 7.0. Kwi-Rhodococcus spp. I-N6, umlinganiselo ophezulu wekhabhoni ukuya kwi-nitrogen (C:N) kunye nokunciphisa isinyithi zezona meko zilungileyo zokuveliswa kwee-biosurfactants ezingaphandle kweseli (Mutalik et al., 2008). Kuye kwenziwa imizamo yokuphucula i-biosynthesis yee-biosurfactants (ii-surfactins) ngokuphucula iintlobo kunye nokubiliswa. Nangona kunjalo, i-titer ye-surfactant kwindawo yokukhulisa isityalo iphantsi (1.0 g/L), nto leyo ebangela umngeni kwimveliso enkulu (Jiao et al., 2017; Wu et al., 2019). Ke ngoko, iindlela zobunjineli bemfuza zisetyenzisiwe ukuphucula i-biosynthesis yayo. Nangona kunjalo, ukuguqulwa kwayo kobunjineli kunzima ngenxa yobukhulu obukhulu be-operon (∼25 kb) kunye nolawulo oluntsonkothileyo lwe-biosynthetic lwenkqubo yokuva i-quorum (Jiao et al., 2017; Wu et al., 2019). Kuye kwenziwa utshintsho oluninzi lobunjineli bemfuza kwibhaktheriya yeBacillus, ikakhulu ejolise ekwandiseni imveliso ye-surfactin ngokutshintsha i-promoter (srfA operon), ukuveza ngokugqithisileyo iproteni yokuthumela ngaphandle ye-surfactin iYerP kunye nezinto ezilawulayo iComX kunye nePhrC (Jiao et al., 2017). Nangona kunjalo, ezi ndlela zobunjineli bemfuza zifezekise utshintsho olunye okanye ezimbalwa zemfuza kwaye azikafikeleli kwimveliso yorhwebo. Ke ngoko, kufuneka uphando olongezelelweyo lweendlela zokuphucula ezisekelwe kulwazi.
Izifundo zokubola kwe-PAH zenziwa ikakhulu phantsi kweemeko zelebhu eziqhelekileyo. Nangona kunjalo, kwiindawo ezingcolisiweyo okanye kwiindawo ezingcolisiweyo, izinto ezininzi ezingabonakaliyo kunye ne-biotic (ubushushu, i-pH, ioksijini, ukufumaneka kwezondlo, ukufumaneka kwe-substrate, ezinye ii-xenobiotics, ukuthintela imveliso yokugqibela, njl.njl.) zibonakalisiwe ukuba zitshintsha kwaye ziphembelela amandla okubola kweentsholongwane.
Ubushushu bunempembelelo ebalulekileyo kwi-PAH biodegradation. Njengoko ubushushu busanda, uxinaniso lwe-oxygen enyibilikisiweyo luyehla, nto leyo echaphazela imetabolism ye-aerobic microorganisms, kuba zifuna i-molecular oxygen njengenye ye-substrates ze-oxygenases ezenza i-hydroxylation okanye i-ring cleavage reactions. Kudla ngokuqatshelwa ukuba ubushushu obuphezulu buguqula ii-PAHs ezizalayo zibe ziikhompawundi ezinobuthi ngakumbi, ngaloo ndlela zithintela i-biodegradation (Muller et al., 1998).
Kuye kwaphawulwa ukuba iindawo ezininzi ezingcoliswe yi-PAH zinexabiso eliphezulu le-pH, njengeendawo ezingcoliswe yi-acid mine drainage (pH 1–4) kunye neendawo zegesi yendalo/amalahle ezingcoliswe yi-alkaline leachate (pH 8–12). Ezi meko zinokuchaphazela kakhulu inkqubo yokubola kwezinto eziphilayo. Ke ngoko, ngaphambi kokusebenzisa ii-microorganisms kwi-bioremediation, kucetyiswa ukuba ulungise i-pH ngokongeza iikhemikhali ezifanelekileyo (ezinamandla okunciphisa i-oxidation aphakathi ukuya kwaphantsi kakhulu) ezifana ne-ammonium sulfate okanye i-ammonium nitrate kwimihlaba ye-alkaline okanye i-liming ene-calcium carbonate okanye i-magnesium carbonate kwiindawo ezine-acidic (Bowlen et al. 1995; Gupta kunye noSar 2020).
Ukunikezelwa kweoksijini kwindawo echaphazelekayo yeyona nto ithintela izinga lokubola kwe-PAH. Ngenxa yeemeko ze-redox zendalo, iinkqubo ze-in situ bioremediation zihlala zifuna ukufakwa kweoksijini kwimithombo yangaphandle (ukulima, ukomisa umoya, kunye nokongezwa kweekhemikhali) (Pardieck et al., 1992). U-Odenkranz et al. (1996) babonise ukuba ukongezwa kwe-magnesium peroxide (i-compound ekhupha ioksijini) kwi-aquifer engcolileyo kunokulungisa ngokufanelekileyo iikhompawundi ze-BTEX. Olunye uphando luphande ngokuchithwa kwe-phenol kunye ne-BTEX kwi-aquifer engcolileyo ngokufaka i-sodium nitrate kunye nokwakha imigodi yokukhupha ukuze kufezekiswe ukulungiswa kweoksijini ngokufanelekileyo (Bewley kunye noWebb, 2001).