Plastic pollutes our environment, especially the seas. However, researchers are increasingly finding small creatures that can digest plastics. Are they the solution to our garbage problem?
Plastic is tough. A discarded PET bottle can remain in the road trench for decades, without it decaying. If the plastic is simply dumped in landfills or landed in the forest, not much will happen – except that the garbage becomes a problem increasingly.
While discarded banana husks are weathering, the smallest organisms are growing, microorganisms reject PET, PE and other plastics. At least it was thought for a long time.
In 2015, Japanese scientists discovered Ideonella sakaiensis on a landfill. The bacterium can utilize PET (the substance from which, among other things, drinking bottles are made), and feed on it. It has adapted through evolution to the conditions of a world dominated by man.
And also the larvae of the wax moth can probably dismantle plastic. In a study published, biologist Federica Bertocchini reports of her accidental observation: when she cleaned a bee hive, she threw larvae into a plastic bag. Sometime later, they had eaten big holes in the bag.
If the larvae can actually break down polyethylene into their basic components and use them as food and not simply crush and separate them, then this would be a medium-sized sensation. Polyethlyene (PE) is extremely stable and difficult to decompose due to its carbon backbone. At the same time, it is much more common than PET.
In the digestive tract of the waxy moth larvae, there are probably bacteria, or their enzymes, which can break down plastic. Even bacteria like Ideonella sakaiensis use enzymes to split the polymers.
The metabolic processes of the bacteria can then be adapted in such a way that the degradation products can be isolated and used in insulin production.
Blank is currently working with bacteria that can convert PET into bio-plastic. For this purpose, the plastic is comminuted, and short monomers are again formed from the long polymer chains.
The bacteria produce bio-plastic from it. To get there, one must dissolve the bacteria and then extract the bioplastics. Blank and his team are currently working on it that the bacterium, when it is marginal, is itself disassembled.
It would be even more practical if the bacteria excrete the bioplastics in small plasticizers and continue to live and eat.
This approach from plastic waste to make valuable substances and one could also transfer to other plastics. If the wax moth larvae actually produce enzymes that degrade PE, then one could apply these proteins one by one.
The advantage is that the bacteria do not care if a plastic is dirty – but this is a problem for other recycling methods. Bacteria would also get along better with mixed plastic. For Bornscheuer, biotechnological processes are becoming more environmentally friendly because they are chemically opposed to the chemical.
But this is not enough to solve the plastic waste problem. If no one collects the garbage, you can not use it. But the importance of biological processes will continue to increase, Bornscheuer is certain. Because there are probably more microorganisms that can digest plastics.