Scientists from Novgorod State University, together with colleagues from Lomonosov Moscow State University and the P. P. Shirshov Institute of Oceanology of the Russian Academy of Sciences, studied bacteria that live in the Barents Sea on plastic waste. It turned out that many microorganisms not only live on plastic, but also feed on it. Scientists have identified them and discovered both known strains for this region and one new species. The research could potentially help in the fight against plastic pollution in the Arctic.
Plastic pollution is a huge problem that has long gone beyond large cities and coastal waters, and has already reached the most remote regions of the planet, including the western parts of the Arctic Ocean. Plastic debris is brought here by currents from the North Atlantic. It also enters Arctic waters with waste from shipping and fishing developed in this region.
Scientists estimate that the amount of macroplastics in the surface waters of the Barents Sea can reach 650,000 particles per square kilometer. In their opinion, microorganisms can help solve this problem. The ability of some bacteria to feed on plastic has already become the main one for the biotechnological method of recycling plastic waste — biocomposting.
The authors isolated bacterial cultures from a build-up (plastisphere) that they formed on marine plastic waste (PET — polyethylene terephthalate, polyethylene, polypropylene, and polystyrene). Samples were collected in the coastal ebb and flow zone in the area of two bays of the Barents Sea — Zelenetskaya and Podpakhta, as well as in the Kola Bay, during summer expeditions in 2021-2023.
After washing the bacteria off the plastic, the scientists placed them on a special nutrient-rich mineral medium that did not contain organic matter. The only source of carbon and energy for microorganisms in this environment was a type of plastic added as a powder, fiber, or emulsion. In this way, the scientists tested the bacteria for "taste preferences" — if the colony began to grow, it meant that it could use plastic for food. The criteria for the ability of bacteria to decompose plastic were also: a decrease in its mass during the cultivation of microorganisms on it, visual damage to the plastic surface — the so-called bioerosion, as well as the absence of bacterial growth in a plastic-free environment.
To determine exactly how bacteria destroy waste — to see damage to the molecular structure of plastic — the authors used the Fourier transform infrared spectroscopy (IR-Fourier) method. It allows you to assess the state of chemical bonds inside a molecule, as if removing "fingerprints" from it — spectral peaks. By comparing such peaks in intact plastic and the one on which bacteria lived for at least 40 days, the scientists were able to see the pattern of changes in the structure of the molecules. Some of the plastic was "eaten away" by microorganisms — the chemical bonds in such samples were damaged.
The third stage of the work was the identification of the types of microorganisms that fed on plastic. To do this, the scientists deciphered a section of the 16S rRNA gene in each strain, the sequence analysis of which makes it possible to determine the culture's affiliation with accuracy to the genus. As a result, nine cultures of microorganisms were isolated. Five of them turned out to be "residents" of PET, two of them of polyethylene, and one each of polypropylene and polystyrene. Seven out of nine crops have successfully passed the plastic nutrition test. Thus, scientists have shown that these species can use it as their only food source.
At the same time, some of the cultures turned out to be well—known to scientists - bacteria of the genera Rhodococcus, Pseudomonas, Pseudoalteromonas, and Rhodopirellula. Such microorganisms have already been found in the plastispheres of the Arctic region. The newcomer was the bacterium Persicitalea sp. — it was first identified in growths on plastic in the Arctic seas.
According to scientists, the study of plastic biodegradation processes is still at the initial stage of study. The next step is to understand the possibilities of using bacteria to break down plastic waste in technological schemes.
Please note that this press release is based on materials provided by the company. AK&M Information Agency shall not be held liable for its contents, nor for the legal and other consequences of its publication.
