The plastic time bomb: Way out of the crisis:
Bacteria - the key to plastic degradation?
Graphic: DNA bacteria
Small crude oil residues have been deposited on the walls of an old port in Hamburg for over 100 years. Pollution in the silt with a chemical structure very similar to plastic. And this is exactly where scientists are looking for bacteria. Bacteria that break down oil residues to generate energy from them - and which can then also decompose plastic.
Even though there are hundreds of different types of plastic, they have one property in common: The plastics consist of long polymer chains that are difficult to degrade. Only certain bacteria produce special enzymes that can break down the polymers. Only when the long chains are “broken down” with the help of the enzymes can the bacteria break them down further. The researchers want to isolate the special enzymes in the bacteria. But to do this, they first have to find the right bacteria in the mud sample. Not an easy task: The sample contains up to 10,000 different types of bacteria, of which perhaps only one produces a suitable enzyme. After months of analyzing a wide variety of samples, the first success is evident: the structure of an enzyme indicates the ability to cleave plastic polymers. And there have even been indications of other enzymes.
A big problem with plastic mining is also the many different types of plastic. A mixture that can be separated - if at all - only with great effort. But that is the prerequisite for being able to effectively process or dismantle plastic. The result of the enzyme test: Two enzymes are effective - up to ten times more effective than already known. An enzyme that decomposes several types of plastic has not yet been found. Until a technical application becomes possible, the effectiveness of the enzymes has to be increased by at least a factor of 1,000. For example, in the basins of sewage treatment plants they could then be used for plastic mining.