{"id":33826,"date":"2019-04-15T05:00:40","date_gmt":"2019-04-15T02:00:40","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=33826"},"modified":"2019-04-15T04:53:07","modified_gmt":"2019-04-15T01:53:07","slug":"evrimin-insanliga-kiyagi-plastik-yiyen-ideonella-sakaiensis","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2019\/04\/15\/evrimin-insanliga-kiyagi-plastik-yiyen-ideonella-sakaiensis","title":{"rendered":"Evrimin insanl\u0131\u011fa k\u0131ya\u011f\u0131: Plastik yiyen Ideonella sakaiensis"},"content":{"rendered":"

Plastiklerden ne vazge\u00e7ebiliyoruz ne kurtulabiliyoruz. Bir yandan her i\u015fimizi g\u00f6r\u00fcyorlar, di\u011fer yandan yeralt\u0131 sular\u0131ndan okyanuslara, soludu\u011fumuz havadan besin zincirinin en k\u0131y\u0131da kalm\u0131\u015f halkas\u0131na, bo\u011faz\u0131m\u0131za kadar plasti\u011fe batm\u0131\u015f durumday\u0131z. Zira her y\u0131l yakla\u015f\u0131k 50 milyon ton miktar\u0131nda \u00fcretilen PET polimerinin ancak \u00e7ok k\u00fc\u00e7\u00fck bir k\u0131sm\u0131 geri d\u00f6n\u00fc\u015f\u00fcme u\u011fruyor; o da pahal\u0131 ve a\u015f\u0131r\u0131 enerji harcayan mekanizmalarla. Ayr\u0131ca \u00fcretim s\u00fcrecine ham petrol eklenmesini gerektiren geri d\u00f6n\u00fc\u015f\u00fcm i\u015fleminin ortaya \u00e7\u0131kard\u0131\u011f\u0131 \u00fcr\u00fcn, nitelik bak\u0131m\u0131ndan ilk \u00fcr\u00fcn\u00fcn seviyesini yakalayam\u0131yor. Hal b\u00f6yleyken bu i\u015fe s\u00fcrd\u00fclebilir, makul bir \u00e7are aray\u0131\u015f\u0131ndaki biliminsanlar\u0131n\u0131n yard\u0131m\u0131na yine malum kurtar\u0131c\u0131m\u0131z yeti\u015fti: Bakteriler.
\n<\/span>\u0130lk defa 2016\u2019da, Japonya\u2019dan bir ara\u015ft\u0131rma ekibinin laboratuvar tezg\u00e2h\u0131na d\u00fc\u015fen bu seferki bakterinin bizim a\u00e7\u0131m\u0131zdan \u00e7ok i\u015fe yarar tuhaf al\u0131\u015fkanl\u0131klar\u0131 var. Kendisi PET \u00fczerinde b\u00fcy\u00fcyor ve b\u00fcy\u00fck \u00f6l\u00e7\u00fcde bununla besleniyor. S\u00f6z\u00fcn k\u0131sas\u0131 plastik yiyor diyelim\u2026 Peki bunu nas\u0131l yap\u0131yor? Do\u011fan\u0131n hikmeti i\u015fte! <\/span>Ideonella sakaiensis<\/span><\/i> isimli bakteri PET polimerini sindirebilen iki \u00f6zel enzim i\u00e7eriyor: PETaz ve MHETaz, yani polietilen tereftalataz ile mono-2-hidroksietil tereftalataz. PETaz\u2019\u0131n i\u015fi plasti\u011fi k\u00fc\u00e7\u00fck PET yap\u0131l\u0131 yap\u0131ta\u015flar\u0131na ay\u0131rmak, en ba\u015fta da MHET\u2019e. Akabinde devreye giren MHETaz\u2019\u0131n g\u00f6revi ise MHET\u2019i, plasti\u011fin ana maddesi olan PET\u2019in iki temel yap\u0131ta\u015f\u0131na, yani tereftalik asit ve etilen glikole ayr\u0131\u015ft\u0131rmak. Bakteriyel sindirim s\u00fcrecinin bu seviyeye kadar inmesi, bizim a\u00e7\u0131m\u0131zdan harika bir sonu\u00e7 do\u011furmaya aday. \u00c7\u00fcnk\u00fc PET\u2019in yeniden sentezlenmesi a\u00e7\u0131s\u0131ndan hayati \u00f6neme sahip bu iki bile\u015fenin s\u00f6z konusu yolla firesiz elde edilmesi, geri d\u00f6n\u00fc\u015f\u00fcm mekanizmas\u0131ndan ham petrol eklenmesi basama\u011f\u0131n\u0131n otomatik olarak \u00e7\u0131kmas\u0131n\u0131 sa\u011fl\u0131yor. B\u00f6ylece hi\u00e7bir kay\u0131p g\u00f6stermeyen ya da ilave bile\u015fen gerektirmeyen, d\u00f6ng\u00fcs\u00fcn\u00fc kendi i\u00e7inde tamamlayan, dolay\u0131s\u0131yla s\u00fcrd\u00fcr\u00fclebilirli\u011fi y\u00fcksek plastik \u00fcretimi ve geri d\u00f6n\u00fc\u015f\u00fcm\u00fc, \u00e7ok yak\u0131nda m\u00fcmk\u00fcn olacak gibi g\u00f6z\u00fck\u00fcyor.
\n<\/span>\u2018Ben bu haberi bir yerlerden hat\u0131rl\u0131yorum\u2019 diyenler olabilir. Haks\u0131z de\u011filler. Zira bu iki basamakl\u0131k mekanizman\u0131n ilk aya\u011f\u0131 olan PETaz\u2019\u0131n yap\u0131s\u0131 yakla\u015f\u0131k bir sene \u00f6nce, 2018 Nisan\u2019\u0131nda \u00e7\u00f6z\u00fclm\u00fc\u015f ve \u2018Plastik yiyen bakteri\u2019 ba\u015fl\u0131\u011f\u0131yla haberlere konu olmu\u015ftu. <\/span>Nature Communications<\/span><\/i>\u2019\u0131n 12 Nisan 2019 say\u0131s\u0131nda yer bulan, konuyla ilgili son makale ise bu sefer MHETaz\u2019\u0131n yap\u0131s\u0131n\u0131n inceliklerini anlat\u0131yor. Yani bahsi ge\u00e7en ba\u015fl\u0131klar\u0131 atmak i\u00e7in o zaman biraz erkendi, \u015fimdiyse tam zaman\u0131! \u00dcstelik MHETaz enziminin PET\u2019in par\u00e7alanmas\u0131ndaki pay\u0131 PETaz\u2019dan bile daha kritik; zira her bir MHETaz molek\u00fcl\u00fc 600 aminoasitten, yani yakla\u015f\u0131k 4000 atomdan olu\u015fan \u00e7ok daha b\u00fcy\u00fck ve karma\u015f\u0131k bir yap\u0131da; bu da PETaz\u2019\u0131n iki kat\u0131 b\u00fcy\u00fckl\u00fc\u011f\u00fcndeki y\u00fczeyiyle MHETaz\u2019\u0131 PET\u2019in par\u00e7alanmas\u0131 s\u00fcrecindeki as\u0131l kahraman yap\u0131yor. Plasti\u011fin par\u00e7alanmas\u0131n\u0131 bu sayede optimize edecek olan bu geli\u015fmeyi her ikisi de Berlin\u2019de bulunan Helmholtz Malzeme ve Enerji Merkezi ile Freie \u00dcniversitesi ara\u015ft\u0131rmac\u0131lar\u0131n\u0131n \u00e7abalar\u0131na bor\u00e7luyuz.
\n<\/span>Bu arada \u015fu hakl\u0131 soruyu sorabilirsiniz: Madem bu iki enzimi ta\u015f\u0131yan bir bakteri do\u011fada zaten mevcut, o halde neden h\u00e2l\u00e2 plasti\u011fin yok olmamas\u0131 gibi sorunumuz var? Bir defa takdir edersiniz ki plastiklerin bu \u00f6l\u00e7ekte hayat\u0131m\u0131za girmesinin ancak yirmi-otuz y\u0131ll\u0131k bir ge\u00e7mi\u015fi var. Dolay\u0131s\u0131yla PET \u00fczerinde b\u00fcy\u00fcmek ve ondan beslenmek bu bakterinin, plasti\u011fin yayg\u0131nla\u015fmas\u0131yla birlikte geli\u015ftirdi\u011fi yeni bir adaptasyon, bir evrim. Ancak, h\u0131zla \u00fcremesi sayesinde adaptasyonunu m\u00fckemmelle\u015ftirmek i\u00e7in bolca zaman\u0131 da olsa <\/span>Ideonella sakaiensis<\/span><\/i>\u2019in PETaz ve MHETaz enzimleri hen\u00fcz kusursuz etkinli\u011fe ula\u015fm\u0131\u015f de\u011fil. Ne de olsa evrim deneme yan\u0131lma ile ilerleyen, vakit alan bir mekanizma. Fakat evrimin ya da do\u011fan\u0131n elinden hi\u00e7bir \u015fey ka\u00e7mad\u0131\u011f\u0131 gibi, insan\u0131n, ya da bilimle u\u011fra\u015fanlar\u0131n diyelim, elinden de hi\u00e7bir \u015fey kurtulmuyor. Ara\u015ft\u0131rmac\u0131lar\u0131n \u00f6zellikle son bir y\u0131ld\u0131r MHETaz \u00fczerinde y\u00fcr\u00fctt\u00fckleri incelemeler, enzimin MHET\u2019e nereden ba\u011fland\u0131\u011f\u0131n\u0131 ve hangi \u015fartlar alt\u0131nda kesim i\u015fleminin ger\u00e7ekle\u015fti\u011fini g\u00f6sterdi. G\u00f6r\u00fcnen o ki MHETaz\u2019\u0131 b\u00fct\u00fcn potansiyelini kullanmas\u0131 i\u00e7in ilave enzimlerle y\u00fcreklendirecek stratejiler geli\u015ftirmek gerekiyor. Dahas\u0131 orta vadede do\u011fal MHETaz\u2019\u0131n, faaliyet d\u00fczeyi \u00e7ok daha y\u00fcksek, hatta mesela BHET gibi PET par\u00e7alanmas\u0131n\u0131n ba\u015fka ara \u00fcr\u00fcnleri \u00fczerinde de etkili olabilecek varyantlar\u0131n\u0131 \u00fcretmek m\u00fcmk\u00fcn olabilir.
\n<\/span>Sonu\u00e7ta do\u011fa her durum ve ko\u015ful i\u00e7in hayal g\u00fcc\u00fcm\u00fcz\u00fcn \u00e7ok \u00f6tesinde, say\u0131s\u0131z senaryo sunuyor. Neyse ki d\u00fcnyada sadece t\u00fcketenler de\u011fil, b\u00fct\u00fcn duyular\u0131n\u0131 bu senaryolar\u0131n inceliklerini ve derinli\u011fini anlamaya vakfetmi\u015f olanlar da var. Yoksa ancak %1\u2019inden haberdar oldu\u011fumuz 1 trilyon bakteri t\u00fcr\u00fc aras\u0131nda <\/span>Ideonella sakaiensis<\/span><\/i>\u2019i fark etmek yerine kendi \u00e7\u00f6p\u00fcm\u00fczde bo\u011fulacakt\u0131k.<\/span><\/p>\n

Kaynak
\n<\/b>1) \u201cMolecular scissors for plastic waste\u201d, Helmholtz-Zentrum Berlin News, 12 Nisan 2019.
\n<\/span>2) Gottfried J. Palm ve ark.,<\/span> \u201cStructure of the plastic-degrading <\/span>Ideonella sakaiensis<\/span><\/em> MHETase bound to a substrate\u201d, <\/span>Nature Communications<\/span><\/i><\/em> 10, 12 Nisan 2019.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Plastiklerden ne vazge\u00e7ebiliyoruz ne kurtulabiliyoruz. Bir yandan her i\u015fimizi g\u00f6r\u00fcyorlar, di\u011fer yandan yeralt\u0131 sular\u0131ndan okyanuslara, soludu\u011fumuz havadan besin zincirinin en k\u0131y\u0131da kalm\u0131\u015f halkas\u0131na, bo\u011faz\u0131m\u0131za kadar plasti\u011fe batm\u0131\u015f durumday\u0131z. Zira her y\u0131l yakla\u015f\u0131k 50 milyon ton miktar\u0131nda \u00fcretilen PET polimerinin ancak \u00e7ok k\u00fc\u00e7\u00fck bir k\u0131sm\u0131 geri d\u00f6n\u00fc\u015f\u00fcme u\u011fruyor; o da pahal\u0131 ve a\u015f\u0131r\u0131 enerji harcayan mekanizmalarla. […]<\/p>\n","protected":false},"author":184,"featured_media":33831,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[19,4692,4747],"tags":[4783,4782,3291],"class_list":["post-33826","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bilim-gundemi","category-biyokimya","category-biyoteknoloji","tag-ideonella-sakaiensis","tag-petaz-ve-mhetaz-enzimi","tag-plastik-geri-donusumu"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts\/33826","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/users\/184"}],"replies":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/comments?post=33826"}],"version-history":[{"count":0,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts\/33826\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/media\/33831"}],"wp:attachment":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/media?parent=33826"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/categories?post=33826"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/tags?post=33826"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}