It’s the Bac- man!

The Star Malaysia - Star2 - - SCIENCE TECH HEAD - A

A TEAM of Ja­panese sci­en­tists has found a species of bac­te­ria that eats the type of plas­tic found in most dis­pos­able wa­ter bot­tles.

The dis­cov­ery, pub­lished a few days ago in the jour­nal Sci­ence, could lead to new meth­ods to man­age the more than 50 mil­lion tons of this par­tic­u­lar type of plas­tic pro­duced glob­ally each year.

The plas­tic found in wa­ter bot­tles is known as poly­eth­yl­ene terepha­late, or PET. It is also found in polyester cloth­ing, frozen- din­ner trays and blis­ter pack­ag­ing.

“If you walk down the aisle in Wal- Mart, you’re see­ing a lot of PET,” said Tracy Min­cer, who stud­ies plas­tics in the ocean at the Woods Hole Oceano­graphic In­sti­tu­tion in Mas­sachusetts.

Part of the ap­peal of PET is that it is light­weight, colour­less and strong. How­ever, it has also been no­to­ri­ously re­sis­tant to be­ing bro­ken down by mi­crobes – what ex­perts call “biodegra­da­tion”.

Pre­vi­ous stud­ies had found a few species of fungi can grow on PET, but un­til now, no one had found any mi­crobes that can eat it.

To find the plas­tic- eat­ing bac­terium de­scribed in the study, the Ja­panese re­search team from Ky­oto In­sti­tute of Tech­nol­ogy and Keio Univer­sity col­lected 250 PET­con­tam­i­nated sam­ples in­clud­ing sed­i­ment, soil and waste­water from a plas­tic bot­tle re­cy­cling site.

Next, they screened the mi­crobes liv­ing on the sam­ples to see whether any of them were eat­ing the PET and us­ing it to grow.

They orig­i­nally found a con­sor­tium of bugs that ap­peared to break down a PET film, but they even­tu­ally dis­cov­ered that just one of bac­te­ria species was re­spon­si­ble for the PET degra­da­tion. They named it ideonella sakaine­sis.

Fur­ther tests in the lab re­vealed that it used two en­zymes to break down the PET. Af­ter ad­her­ing to the PET sur­face, the bac­te­ria se­cretes one en­zyme onto the PET to gen­er­ate an in­ter­me­di­ate chem­i­cal. That chem­i­cal is then taken up by the cell, where an­other en­zyme breaks it down even fur­ther, pro­vid­ing the bac­te­ria with car­bon and en­ergy to grow.

The re­searchers re­port that a com­mu­nity of Ideonella sakaien­sis work­ing this way could break down a thin film of PET over the course of six weeks if the tem­per­a­ture were held at a steady 86 de­grees Fahren­heit.

Min­cer said the study was im­pres­sive and did a good job show­ing that th­ese or­gan­isms were eat­ing the plas­tic pretty well. How­ever, he said it was not im­me­di­ately clear whether or not it would help keep plas­tics out of the ocean, for ex­am­ple.

“When I think it through, I don’t re­ally know where it gets us,” he said. “I don’t see how mi­crobes de­grad­ing plas­tics is any bet­ter than putting plas­tic bot­tles in a re­cy­cling bin so they can be melted down to make new ones.”

He added that the re­search could make it eas­ier to iden­tify other mi­crobes that might have sim­i­lar PET- de­grad­ing ca­pa­bil­i­ties.

“This process could be quite com­mon,” he said. “Now that we know what we are look­ing for, we may see th­ese mi­crobes in many ar­eas around the world.” – Los An­ge­les Times/ Tribune News Ser­vice

A team of Ja­panese sci­en­tists has found a species of bac­te­ria that eats the type of plas­tic found in most dis­pos­able wa­ter bot­tles. — TnS

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