Metabolomic Unravelling and RSM-Assisted Optimization of Phenylpyrazole Degradation by a Novel Soil-Derived Bacterial Consortium FP-25

Fipronil is a phenylpyrazole insecticide that is frequently utilized in agricultural practices. It engenders noteworthy environmental threat owing to its persistence, bioaccumulation, and off-target toxicity. The empirical bioremediation propensity of known fipronil-degrading bacteria is restrained by its inferior efficiency and low environmental resilience. In this study, a novel microbial consortium, FP-25, was concocted by isolating two fipronil-degrading indigenous bacterial strains— Pseudomonas furukawaii strain S4 and Agrobacterium pusense strain S6—from perpetually contaminated agricultural soil. The consortium was appraised for its fipronil degradation propensity in aqueous media. Optimization of biodegradation variables was orchestrated through response surface methodology (RSM) deploying a Box–Behnken design, which methodically analyzed the interactive effects of pH, temperature, inoculum biomass and fipronil concentration. The optimized conditions—32.5°C, neutral pH, and an inoculum concentration of 0.175 g L⁻¹, and 200 mg L ^− 1 fipronil concentration —effectuated degradation efficiencies of 91.92% for consortium FP-25 within 14 days of incubation. The generation of degradation products was certainly corroborated through GC-MS analysis. Consequently, a catabolic pathway for fipronil degradation used by the consortium FP-25 has been explicated, depicting the successive enzymatic transformation of fipronil to non-toxic metabolites. The befitting and the rationality of the RSM model were evaluated through the deployment of an in-situ microcosm experiment, utilizing actual contaminated soil sampled from the Himalayan highland ecosystem. Degradation kinetics substantiated first-order reaction models with rate constants ranging between 0.046 and 0.076 day⁻¹. Thus, the present study endorsed the puissant bioremediation ability of the developed consortium FP-25 as an eco-friendly and sustainable substitute for conventional approaches.