A critical review on occurrence, distribution, environmental impacts and biodegradation of microplastics

Abstract

Microplastics are small plastic particles (<5mm) linked by hydrocarbon atoms. Microplastics are of two types: primary microplastics, which are inadvertently released into the ecosystem as microbeads, plastic pellets and plastic fibres and secondary microplastics, derived from primary microplastics, when macroplastics get decomposed in the presence of UV light or weathering. Sources of contamination by microplastics can be classified as Terrestrial sources and Aquatic Sources. Microplastics are widespread in diverse ecosystems and are spread in different parts of the world, like India, China, Brazil and Malaysia. Recent studies have revealed the toxic effects of microplastics on various biotic and abiotic components. Microplastics can be completely removed from the soil by microbial biodegradation, most preferably bacteria, actinobacteria and fungi. Bacteria, the recurring group of microbes, can degrade pollutants. Actinobacteria, a commonly occurring Gram-positive bacterium, degrade polymer accumulation. Followed by bacteria, fungi are a major group of microorganisms known to degrade microplastics. The current review deals with the type of plastics, their sources, distribution, environmental impacts and degradation using biological methods, preferably microbes, which would further help in understanding the microplastic-mediated adverse effects' molecular mechanism and their removal from the environment using Green Technology. Key words: Biodegradation, Microbes, Microplastics, Toxicity