Degradation of polyethylene microplastics through microbial action by a soil isolate of BreviBacillus brevis

Abstract

The fragmentation of polyethylene plastics into polyethylene microplastics (PEMPs) due to biotic and abiotic factors affects the environment. Extensive investigations have shown its implications upon accumulation in the living systems. In this study, B.brevis was employed to degrade PEMPs. B.brevis-mediated degradation process has shown a reduction in microplastic's dry weight by 19.8% over 35 days of treatment. The biodegradation was achieved by releasing laccase enzyme and organic acids onto the surface of PEMPs, which were quantified by UP-HPLC. Further, the changes in the morphological and structural changes on of PEMPs were observed by TEM, SEM, DSC, TGA, XRD, and FTIR analysis. Additionally, after the degradation, by-products were observed to contain small molecules such as 2-hexadecanone, decanone etc. The small molecules were resulted from the biodegradation of PEMPs and were further utilized for bacterial metabolism. These outcomes reveal the efficiency of B.brevis in PEMPs degradation.