MICROBIAL APPROACH TO CURB MICROPLASTIC POLLUTION
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Microplastic refers to the tiny pieces of plastics formed by the breakdown of plastic products. Even after being discovered for over a decade, it recently gathered attention of the environmentalists for its growing abundance in the world's ocean. According to a survey, around 8.8 million tonne of microplastics are introduced into the ocean every year.
Several domestic or industrial products like textile fibers, cosmetics, domestic washings, fishing nets, packaging materials etc. contain plastics of diameter 5mm or less that are difficult to recycle. As it's concentration increases, a mass of debris is formed that later contaminates coastal sediments as well as in water bodies like lakes, estuaries and oceans. A recent study also found microplastics suspended in tap water.
Microplastics actively make their way into the food chain. The particles are engulfed by aquatic organisms like fish, mussels etc. where they get bio accumulated, and further biomagnified to reach organisms at higher trophic levels. While microplastic toxicity in aquatic organisms is already known, various groups of scientists are trying to identify its adverse effects on human health. Several cases of microplastics isolated out of human organs are coming up. In such conditions, it has become very essential to contain these micropollutants as soon as possible. What worsens the situation is the inability to monitor and degrade these plastics effectively.
Several methods are being developed by researchers to curb this issue. However, microplastic passage through aquatic channels is taken more into consideration to block its entry into the oceans, it is believed that removal of microplastic from the origin level could be highly effective in reducing the microplastic concentration in the oceans.
According to a recent study published in Chemical Engineering Journal, A group of professors from The Hong Kong Polytechnic University, Kowloon developed a "trap and release" mechanism for microplastic removal using microbes. The study used the biofilm forming ability of genetically engineered bacteria Pseudomonas aeruginosa to form aggregates of microplastics that get trapped within its sticky extracellular matrix. These aggregates were later released and recycled. The method is beneficial over currently available filtration methods because it can trap microplastics irrespective of its size. Also aggregate formation would be a lot easier in the regions with high concentration of microplastics, which would improve the ability to filter or sediment the micro pollutants from highly contaminated sewage water. Proper regulation of intracellular c-di-GMP secondary messenger signaling responsible for biofilm formation can readily help bacteria to aggregate and later disperse the collected microplastics.
While plastic degradation is a risky process because of its varied chemical composition, using microbial biofilm for mass removal of microplastics would be a faster, cost-effective and sustainable alternative for treating sewage or industrial waste water tanks. We need to investigate more into the removal efficiency that will separate high and low density microplastic aggregates effectively and make this study a potential tool for industrial application.
● Yang Liu, S., Ming-Lok Leung, M., Kar-Hei Fang, J., & Lin Chua, S. (2020). Engineering a microbial “trap and release” mechanism for microplastics removal. Chemical Engineering Journal, 127079. doi:10.1016/j.cej.2020.127079
Abhaya Dayini Behera
Treillis Life Sciences Pvt. Ltd