Microbial Degradation of Micro‐Plastics

Plastic production and usage has witnessed an exponential increase across the globe in this century. This has increased its presence in every niche of the biosphere and is adding to the ever-growing pollution on the Earth. Recently, the production of bio-based plastics has gained momentum, but complete swapping of the fossil-based polymer will be a long journey. Due to their persistent nature, non-biodegradable plastics cause adverse effects on the health of the flora and fauna. Plastics have entered the food chain and this leads to their biomagnification. Over time, the plastics undergo some wear and tear, and have been found to be broken down into particles as small as 5 mm, which are called microplastics (MPs). The presence of these MPs has been found to increase in our natural habitats both on land and in water bodies such as lakes, rivers, estuaries, and oceans. The degradation of these microplastics has been helped by the presence of naturally occurring microbes such as diatoms, dinoflagellates, cyanobacteria, barnacles, bryozoans, isopods, heterotrophic bacteria, and fungi. These microbes have been reported to use plastics as a carbon source in their respiratory metabolic pathways, but these microbes are not constant, and it has been observed that they may vary from one ecological niche to the other depending on the local environmental conditions. There is much research ongoing to understand this phenomenon so that it can be effectively used for bioremediation. Recently, the microbial enzymes are being exploited for their potential of degrading polymers. As far as the water contamination with MPs is concerned, further advancement to control MP contamination has been performed with physical methods such as with disc filter, rapid sand filtration, dissolved air floatation, and membrane bioreactors. Research is required to obtain a clear understanding of the microbes that may be efficient bioremediators for the MPs, and if the physical technologies along with these microbes and microbial enzyme-based biotechnologies can be employed for tackling the challenge of the bioremediation of the MP pollution in our environment.