Navpreet Kaur, Mridula Chaturvedi, Samsul Alam, Shashi Sharma
The extensive use of pesticides has led to persistent agroecosystem contamination, increasing environmental and human-health risks. Rationally designed multifunctional microbial consortia offer a sustainable strategy for degrading complex pesticide mixtures, yet most are empirically assembled, emphasizing degradation efficiency, overlooking pesticide bioavailability and soil restoration. The role of biosurfactant (BS) producing bacteria as keystone members during consortium-based bioremediation remains underexplored. In the present study, 17 Risk Group 1 bacterial isolates exhibiting pesticide degradation, BS production, and plant growth-promoting (PGP) traits were assembled into three hexa-bacterial consortia (CI, CII, and CIII), each comprising Gram + ve and Gram -ve bacteria. The consortia were evaluated for simultaneous degradation of chlorpyrifos, cypermethrin, and lindane (16.66 ppm each) and their functional stability. CI (two BS producers; 2.57 g/L glycolipid) and CII (one BS producer; 2.41 g/L) degraded chlorpyrifos and cypermethrin almost completely, while degraded lindane by 93.6% and 89%, respectively in 8 days. CIII (one BS producer; 2.42 g/L) showed reduced degradation of chlorpyrifos (83.7%) and lindane (71%), while completely degraded cypermethrin. BS production reduced surface tension from 55.8 to 30.3-32.2 mN/m, indicating enhanced solubilization of pesticides and metabolites. Drop-out and replacement of BS producers reduced pesticide degradation and enzyme activities, demonstrating their contribution in solubilization and catabolic performance. In pesticide-amended soil, CI degraded chlorpyrifos, cypermethrin completely and 98.1% lindane in 28 days, with reduced surface tension. Phytotoxicity and microbial toxicity assays confirmed the non-toxic nature of CI metabolites. Overall, strategic incorporation of BS producers and PGP bacteria enhanced pesticide degradation and supported soil restoration.