Enye yezinjini zokuthuthukiswa komnotho engxenyeni yesibili yekhulu leminyaka elidlule kwakuyipulasitiki. Zishibhile, kulula ukukhiqiza, zimelana, ziyanwebeka futhi, uma zixega, zisobala, kodwa zine-b-side, ngoba azikwazi ukubola, ngoba azikho izinto eziphilayo ezikwazi ukuzondla.
Ukuqina kwazo isikhathi eside, ngaphandle kokungabaza, enye yezinselelo ezinkulu esibhekene nazo, njengoba okungenani iminyaka engamakhulu amane namashumi amahlanu kufanele idlule ukuze ama-polymer aqale inqubo yokuhlakazeka ezingeni lamangqamuzana.
Kulinganiselwa ukuthi angaphezu kwezigidi ezingama-300 amathani epulasitiki akhiqizwa emhlabeni jikelele, lapho u-90% wawo uphuma kuwoyela kanti ingxenye encane, cishe u-15%, izobuyiswa futhi itholakale emhlabeni jikelele.
Kuleso samba sezinkanyezi, isilinganiso samathani ayizigidi eziyisishiyagalombili agcina entanta minyaka yonke olwandle lwethu, lapho ecwila khona, anqwabelane othulini noma agcine efakwe ochungechungeni lokudla kwabantu.
Izibikezelo zesikhathi esifushane azilungile neze, amanye amazwi anegunya alinganisela ukuthi ngo-2050 ukukhiqizwa kwemfucuza yepulasitiki kuzofinyelela amathani ayizigidi eziyizinkulungwane eziyishumi nantathu. Isibalo, ngokungangabazeki, esisiphoqa ukuthi sithathe izinyathelo ezinamandla neziphuthumayo.
Siyabonga ngo-2016 sathola ukuba khona komngane okungenzeka futhi, njengoba kwenzekile izikhathi eziningi emlandweni wesayensi, ukuthukuthela kwadlala indima ebalulekile. Kulo nyaka iqembu lososayensi baseJapane liphenye ngamakoloni amagciwane embonini yokugaywa kabusha kwezinto edolobheni laseSakai, eJapane. Ngalesi sikhathi sihlaziye amabhaktheriya akhishwe ezinsalela ze-polyethylene terephthalate (PET) ngaphezu kwengxenye (i-ethylene glycol ne-terephthalic acid).
Bemangele, bathola ukuthi igciwane, elaqanjwa ngokuthi i-Ideonella sakaiensis, lalikwazi ukusebenzisa i-PET njengomthombo oyinhloko wekhabhoni. Ngemva kwesikhathi esithile kwaba nokwenzeka ukukhombisa ukuthi i-microorganism inezakhi zofuzo ezimbili ezibalulekile 'ezingakwazi ukushwabadela' i-PET: i-PETase kanye ne-mono(2-hiroexieethyl) terephthalate hydrolase.
Isixazululo esinethemba
Ukutholakala kochungechunge lwe-metabolic kwenza kwaba nokwenzeka ukuchaza ukuthi kungani i-Ideonella isungule indawo yayo yokuhlala esitshalweni esigaywa kabusha, kodwa osekusele ukuthi kuxazululwe ukuthi yini eye yaba indlela yokuthi amagciwane aguquke ukuze aguqule ipulasitiki, eyayinelungelo lobunikazi ishumi leminyaka lamashumi amane ekhulwini elidlule, emthonjeni walo wokudla.
I-bacterium iyakwazi ukuguqula i-PET ibe yi-poly(3-hydroxybutyrate) - eyaziwa nangokuthi i-PHB - okuwuhlobo lwepulasitiki ebolayo. Isikhalo sale ndaba ukuthi i-PET ilinganiselwa ukuthi izokwehlisa izinga lika-0,13mg ngesentimitha yesikwele ngosuku, ezingeni lokushisa elingu-30ºC, izinga lokuqeda eliba 'lihamba kancane kakhulu'.
Inhlanhla yaphinde yamamatheka ngathi ngo-2018 lapho abacwaningi base-Postmouth University (UK) baklama ngephutha i-enzyme ethuthukisa i-PETase yebhaktheriya.
Ngalesi sikhathi, izamile ukuthatha esinye isinyathelo sokukhulisa ukukhiqiza kwayo 'ngokufaka' i-enzyme eguquguqukayo kubhaktheriya ye-extremophile, ekwazi ukumelana nezinga lokushisa elingaphezu kuka-70ºC, isibalo lapho i-PET ibukeka kakhulu. Lokhu 'kudlulisa' kungase kusheshise inqubo yokwehlisa izinga kufika ku-10%.
Konke lokhu okutholakele kungasinika ikhefu futhi kuvule iwindi lethemba, njengoba amagciwane 'ashwabadela amapulasitiki' angaba yingxenye yesixazululo senkinga yemvelo ebangelwa amapulasitiki.
UMnu Jara
UPedro Gargantilla uyi-internist esibhedlela i-El Escorial (Madrid) futhi ungumbhali wezincwadi ezimbalwa ezidumile.
