Biofilm-mediated surface depolymerization of multiple synthetic polymers by mangrove-derived bacterial consortia

Plastic pollution persists across marine and terrestrial ecosystems largely due to the intrinsic resistance of synthetic polymers to biological attack. Despite growing evidence of microbial interactions with plastics, the mechanistic basis and extent of biofilm-mediated polymer deterioration remain poorly constrained. Here, we investigate the capacity of mangrove-derived bacterial consortia to initiate early-stage degradation of major synthetic polymers (PET, PS, LDPE, HDPE, and PP) under controlled laboratory conditions. Over a 120-day incubation under controlled laboratory conditions, consortium-exposed polymers exhibited differential mass loss, surface erosion, and mechanical weakening, with PS 20.14% and PET 8.33% showing the highest susceptibility. Integrated surface and molecular analyses using confocal laser scanning microscopy, atomic force microscopy, scanning electron microscopy energy dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy revealed extensive biofilm formation, nanoscale pitting, oxidative functional group incorporation, and localized polymer chain modification. Tensile testing further demonstrated reductions in mechanical integrity consistent with surface-driven structural weakening. First-order kinetic fits were applied to gravimetric data to provide comparative, non-predictive estimates of degradation dynamics across polymer types. This study provides quantitative and mechanistic evidence that environmentally adapted microbial consortia can promote biofilm-driven surface depolymerization, highlighting mangrove sediments as underexplored reservoirs of plastic-interacting microbes. These findings advance current understanding of early-stage plastic biodegradation and inform future strategies for biotechnological intervention in microplastic-polluted environments.