Exploring hydrocarbons as co-substrates in Winogradsky columns towards the development of microbial consortia for accelerating the degradation of low density polyethylene in saline environments.

Low density polyethylene (LDPE) is used extensively in packaging applications due to its flexibility and durability. However, due to its recalcitrant nature, its post-consumption disposal is a major environmental challenge. This study utilizes hydrocarbon co-substrates to investigate the integrated enrichment-based biodegradation of LDPE in a saline environment. To achieve this, Winogradsky columns constructed using dumpsite soils were enriched with hydrocarbons and LDPE under saline conditions. After 180 days, diesel-supplemented systems exhibited a significantly higher weight loss (12.15 ± 2.35 %) than unaided systems (0.24 ± 0.18 %). These systems showed greater surface alterations and a substantial reduction in the water contact angle (48.01 ± 3.46°), indicating increased hydrophilicity of LDPE sheets as compared to unaided systems (67.81 ± 5.06°). Treated LDPE sheets exhibited a significant reduction in crystallinity from 30.98 ± 0.46 % (untreated LDPE) to 26.93 ± 3.39 %. The degradation metabolites of LDPE included oxidation products such as alcohols, ketones, acids, and esters. Enzymatic assays suggest that LDPE degradation was initiated by oxidation via alkane monooxygenase and laccases, with manganese peroxidase aiding polymer weakening and hydrolases acting on downstream oxidation products. These findings underscore the role of hydrocarbons as co-substrates in enhancing the microbial degradation of LDPE under saline conditions.