Introducing the LDPE degrading microbes of sedimentary systems: from dumpsite to laboratory†

Abstract

Plastic pollution is a growing environmental concern, necessitating sustainable degradation solutions. Microbial degradation offers an eco-friendly alternative to conventional disposal methods such as incineration and landfilling. This study investigates the biodegradation potential of a bacterial strain isolated from a plastic-rich dumpsite. Five bacterial isolates were screened, among which the BH-5 strain demonstrated the highest degradation efficiency of 10.5% within 30 days, as determined by weight loss measurements. The bacterial species was identified as Bacillus paramycoides through 16S rRNA gene sequencing. Fourier transform infrared (FTIR) spectroscopy confirmed the degradation process by revealing the appearance of hydroxyl and carbonyl groups (3329.50 cm⁻¹ and 1650.47 cm⁻¹) in the treated low density polyethylene (LDPE) samples, absent in the control. Scanning Electron Microscopy (SEM) further revealed structural modifications, such as cracks and surface erosion, indicating bacterial degradation activity. Optimization of pH and temperature enhanced the biodegradation efficiency, with Bacillus paramycoides showing optimal growth at pH 7 and 30 °C, increasing degradation to 13.8% after 30 days. Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified depolymerized byproducts, including alkanes, alcohols, and fatty acid esters, further validating microbial breakdown. This study highlights Bacillus paramycoides as a promising candidate for the biodegradation of LDPE, offering an environmentally sustainable approach for mitigating plastic pollution. Future research should focus on large-scale applications and enzymatic pathways involved in microbial plastic degradation.