A mechanistic insight into polyethylene degradation by Bacillus sp. and, Lysinibacillus sp. from mangrove soil

Abstract

This study aims to establish a sustainable method for plastic remediation, particularly focusing on polyethylene (PE). Bacteria capable of breaking down PE were identified and characterized from plastic-contaminated mangrove soils in Mangalavanam and Puthuvype, where limited efforts had been made to explore PE-degrading microbes. Two isolates, Ma21 and Pu9, showed efficient PE degradation, which exhibited 7.8 % and 4.2 % weight loss of PE film respectively. This degradation was supported by FTIR analysis, indicating initial degradation steps, and FE-SEM analysis, showing surface deterioration of PE films due to bacterial action. GC-MS analysis of reaction intermediates detected phthalic acid compounds, suggesting the ability of these bacteria to degrade PE and indicating the presence of plastic additives in the degradation medium. Screening for biosurfactant production revealed that both Ma21 and Pu9 can produce biosurfactants. The production of alkane hydroxylase enzyme and laccase enzyme by Ma21 and Pu9 further supported their biodegradation capabilities. Molecular identification through 16S rDNA sequencing confirmed that Ma21 is Bacillus thuringiensis, and Pu9 is Lysinibacillus boronitolerans.