Microbial Degradation of Discarded Microplastic Pollutants by Marine Bacterial Isolates from the Eastern Coast of the Bay of Bengal, India

Discarded marine plastics (DMPs) are emerging marine pollutants that have been attracting general attention for the last decade. This present investigation focuses on the collection, characterization, and distribution analysis of discarded marine plastic samples collected from marine sediments of the Bay of Bengal coast of India, and reports the first-of-its-kind isolation and molecular characterization of microplastics degrading native bacterial strain isolated from Chandipur coast oceanic sediments, Bay of Bengal India. Molecular identification taxonomically identified the bacterial strains as Exiguobacterium sp. and Bacillus amyloliquefacin submitted to NCBI Gene Bank with the accession numbers (ON627837) and (ON653029). The microbial microplastic shearing and screening investigation was carried out by subculturing the isolates on 0.1-gram polyethylene glycol (PEG) supplemented plates. The biodegradation investigation under optimized conditions of 0.5% discarded marine plastic at pH 8 and temperature 32oC resulted in 4% weight loss after 30 days of incubation under a constant shaker each at 200 rpm. Scanning electron microscope and Fourier transform infrared spectroscopy analysis of the microbial-degraded plastics’ surface morphology and composition revealed multiple cracks, free porous, rough, and coagulated precipitates on the surface compared with the control samples' plain and smoother surfaces. The resultant FTIR mean peaks of 453 μm and 3696 μm suggested the presence of PET (37%) as the most predominant polymer, whereas the other polymers like PE (15%), PP (1%) and LDPE (11%) are present in fragments. This investigation emphasizes the significance of the biodegradation properties of the native bacterial isolates while highlighting insights into the metabolic functions and degradability in the natural environment.