Breaking down hard-to-recycle plastic is an important task. If microorganisms can solve it, it will help rid humanity of millions of tons of toxic waste every year.
German scientists have identified a strain of the extremophilic group of bacteria that is capable of absorbing toxic organic compounds, using them as a source of carbon, nitrogen and energy. In the process, they break down some of the chemical building blocks of polyurethane. The authors published an article about this in the publication Frontiers in Microbiology.
Plastic pollution today is one of the main environmental problems of our planet. Waste continues to grow, and despite efforts to recycle, not all plastics are recyclable and end up in landfills. In addition, a large amount of plastic is still simply thrown away, bypassing even a landfill, and ruining wildlife. The work carried out by scientists around the world is trying to bring us closer to solving the main question: how to learn how to make plastic less dangerous.
According to one of the authors, Dr. Hermann Heipiper of the Helmholtz Center for Environmental Research in Leipzig, the results are an important step towards the recyclability of difficult-to-recycle polyurethane products.
Millions of tons of polyurethane products are produced annually in Europe alone. This material, convenient for various industries, is difficult and energy-intensive to process or destroy, since the bulk of such compounds are thermosetting polymers that do not melt when heated. Once discarded, polyurethane waste in landfills or in the wild begins to release toxic chemical compounds over time, and many of these compounds are, among other things, carcinogenic. To make this and other hard-to-recycle plastics completely biodegradable, intermediate processing by microorganisms is needed, which scientists are looking for under a special EU program.
The authors of the study were able to detect and describe the bacterium Pseudomonas sp. TDA1. Experimental results have shown that the microorganism can help by attacking some of the chemical compounds underlying polyurethane plastics. Scientists analyzed their genome and preliminarily identified some of the factors that allow these microscopic creatures to metabolize molecules in polyurethane for energy. In addition, they did additional analyzes and tests to determine the capabilities of this Pseudomonas strain.
The strain isolated by scientists belongs to a group of bacteria that are known for their resistance to toxic organic compounds. The next step to study the find, according to the researchers, will be the identification of genes that code for extracellular enzymes in this bacterium. Such enzymes are capable of cleaving certain chemical compounds in polyester-based polyurethanes. These substances, they are also exozymes, in essence proteins, secreted outside the cell and causing a biochemical reaction.
If the work is successful, it will be possible to talk about more ambitious plans for the creation of biodegradable plastics. Today it is too early to judge the specific possibilities, but it can be assumed that using the methods of synthetic biology, it is possible, for example, the genetic transformation of bacteria into mini-factories capable of converting oil-based chemical compounds into biodegradable ones. For such significant technological and commercial leaps, additional fundamental knowledge is needed, which is created, in particular, by research, such as the current one, step by step.