Brief­ing

Scuba Diver Australasia + Ocean Planet - - Contents -

An in­ad­ver­tently-en­gi­neered cre­ation dis­cov­ered by US Depart­ment of En­ergy’s Na­tional Re­new­able En­ergy Lab­o­ra­tory (NREL) and the UK’s Univer­sity of Portsmouth may of­fer a vi­tal solution to the prob­lem of plas­tic pol­lu­tion.

The PET-di­gest­ing enzyme Ideonella sakaien­sis, also known as PETase, was first dis­cov­ered in 2016 by Yoshida et al., who found the bac­terium liv­ing in the soil at a re­cy­cling plant in Ja­pan that was piled with used bot­tles. This bac­terium was unique as it could use poly­eth­yl­ene tereph­tha­late (PET) as its ma­jor car­bon and en­ergy source. In other words, these bac­te­ria can sim­ply feed on plas­tic used to make dis­pos­able bev­er­age bot­tles for sur­vival and growth.

With this dis­cov­ery, NREL and the Univer­sity of Portsmouth ded­i­cated a re­search team to de­ter­mine the enzyme’s struc­ture. While con­duct­ing the re­search, the team in­ad­ver­tently cre­ated a mu­tant PETase. “We hoped to de­ter­mine its struc­ture to aid in pro­tein en­gi­neer­ing, but we ended up go­ing a step fur­ther and ac­ci­den­tally en­gi­neered an enzyme with im­proved per­for­mance at break­ing down these plas­tics,” ex­plained the re­search team in NREL’s state­ment.

As com­pared to the orig­i­nal enzyme, the mu­tant’s ap­petite has dra­mat­i­cally in­creased and the process of feed­ing has ac­cel­er­ated.

Not only is this new cre­ation more ef­fec­tive than PETase, the dif­fer­en­ti­at­ing fea­ture lies in its abil­ity to con­sume an­other type of plas­tic, poly­eth­yl­ene fu­randi­car­boxy­late (PEF). “It is lit­er­ally drilling holes through the PEF sam­ple. This shows that by us­ing PETase, PEF is even more biodegrad­able than PET,” said NREL’s Gregg Beck­ham, one of the lead­ing re­searchers. This new cre­ation opens a new door to com­bat­ing the huge quan­ti­ties of plas­tic waste en­ter­ing land­fills and ac­cu­mu­lat­ing in the ocean.

ABOVE A moun­tain of plas­tic – a sight most of us are far re­moved from

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