Identification and Evaluation of Soil-Derived Microbial Strains for Thiamethoxam Biodegradation

This study investigates the enrichment, isolation, and characterization of thiamethoxam-degrading bacterial species from cotton field soils. Soil previously exposed to xenobiotics was used to enrich microbial biomass in MSMT broth, leading to the isolation of nine distinct bacterial species based on colony morphology. These isolates were screened for their ability to degrade thiamethoxam in liquid cultures, revealing that bacterial isolate TY achieved the highest degradation rate of 35.52% over 15 days. Taxonomic identification through 16S rDNA sequencing identified isolate TY as a novel strain of Salmonella enterica subsp. enterica with a reduced sequence identity of 96% compared to reference strains. The bacterial isolate TY was non-pathogenic, as determined by Congo red agar assays. Optimal growth conditions for TY were identified at 37°C and pH 6.5, and its thiamethoxam degradation was influenced by the availability of carbon and nitrogen sources. This research highlights the potential of S. enterica strain TY for bioremediation of thiamethoxam and contributes to the understanding of pesticide degradation by non-traditional bacterial species.