The extent of plastic pollution in the oceans is considerable, and it could be that up to 70 percent of the waste in the world’s oceans is made of plastic. Such is the extent of plastic pollution, that microplastic has now entered the human food chain. In addition, the chemicals leached out from plastic are having an adverse effect on marine life.
One mechanism to address plastic pollution in the oceans could be from aquatic microbial life, according to new research.
To assess the possibility of microbial conversion of plastics, microbiologists used particles of polyethylene which were marked with a radioactive isotope . This enabled the researchers to track the path and conversion of the plastic by the microbes.
The tracking process showed that the chemicals that formed the plastic were broken down and transformed into beneficial fatty acids, such as omega-3 and omega-6. This was shown by the application of a technique called stable isotope mass spectrometry.
Commenting on the research, lead scientist Dr. Sami Taipale states: “We wanted to study whether microbes that have the ability to decompose complex humic compounds would also use recalcitrant microplastic polymers, and indeed, microplastic degradation was more pronounced by microbes originating from the humic lakes than from the clear water lakes.”
Humic lakes have been found to contain high amounts of organic acids. Here the types of microorganisms found to be most effective at degrading the plastic were Mixotrophic algae (Cryptomonas sp.) and herbivorous zooplankton (Daphnia magna).
Humic substances are organic compounds which are important components of humus, the major organic fraction of soil and also with dystrophic lakes and ocean water.
The benefit of the process is that fatty acids can be absorbed by animals positioned higher up in the food chain, without any adverse effects (there may even be some benefits from these compounds to marine life).
The researchers suggest that altering the microbial population of an aquatic environment in favour of the microbes that have plastic degrading properties could help to address some of the concerns linked to microplastic pollutants.
The research findings have been published in the journal Scientific Reports. The research paper is titled “Tracing the fate of microplastic carbon in the aquatic food web by compound-specific isotope analysis.”