Enhanced soil biodegradation of low-density polyethylene (LDPE) by a synthetic bacterial consortium: Performance,...

Low-density polyethylene (LDPE) is a persistent plastic that significantly contributes to environmental pollution. Although individual bacterial strains show limited ability to degrade LDPE, synthetic consortia present a promising alternative. This study constructed a synthetic bacterial consortium (GAM), comprising Gordonia sihwensis LS1, Amycolatopsis thermoflava 3B14, and Mesorhizobium sp. 1B3, selected for their complementary traits in LDPE degradation, biofilm formation, biosurfactant production, and nonpathogenic profiles. In liquid culture, the GAM consortium exhibited a higher LDPE degradation rate (0.0007 day^-1) than individual strains (0.0005-0.0006 day^-1), based on a pseudo-first-order kinetic model. The consortium was then applied to soil microcosms. To enhance biodegradability, visible light exposure and deep eutectic solvent (DES) coating were applied alone or combined with bioaugmentation. After 60 days, LDPE weight loss in GAM-treated microcosms ranged from 5.70 % to 7.88 %, compared to 1.66 %-2.37 % in uninoculated microcosms. The LDPE half-life decreased from 1731-2482 days to 504-705 days with consortium inoculation. The greatest degradation occurred when bioaugmentation was combined with both light and DES, with significant differences confirmed statistically (p ≤ 0.05). Scanning electron microscopy and Fourier-transform infrared spectroscopy revealed surface cracking and reduced peak intensities, indicating polymer breakdown. Bacterial community analysis showed the consortium members remained abundant with minimal impact on native microbiota. Genomic analysis identified genes related to LDPE degradation, biofilm formation, and biosurfactant production; however, transcriptomic or proteomic validation is needed to confirm gene expression. These results highlight the GAM consortium's enhanced LDPE degradation potential and the benefit of integrating microbial and physicochemical approaches for plastic waste mitigation.