CHAHAT SHARMA, RAJ SINGH AND POOJA SHARMA*
Department of Bio-Sciences and Technology, MMEC, Maharishi Markandeshwar (Deemed to be) University,
Mullana, Ambala-133 207 (Haryana), India
*(e-mail: pooja0029@gmail.com; Mobile: 92505 86619)
(Received: January 6, 2026; Accepted: February 6, 2026)
ABSTRACT
Xenobiotic compounds such as utilization of pesticides are a major cause of greenhouse gases influx in atmosphere. Persistent pesticide accumulation in soil poses serious threats to microbial diversity, ecosystem stability and food safety. The present study aimed at evaluating the pesticide-degrading efficiency of nitrogen-fixing bacterial isolates obtained from cereal-crop rhizospheres. Sixteen diazotrophic isolates were screened for their ability to tolerate and degrade commonly used neonicotinoid pesticide thiamethoxam, under laboratory conditions. Primary and secondary screening identified several isolates exhibiting high tolerance and potential for xenobiotic degradation. Primary screening involved qualitative analysis using MSM agar plate enriched with various concentrations of thiamethoxam (10, 50 and 100 ppm) to evaluate the tolerance by growing nitrogen fixing bacterial isolates on it. Tolerant isolate s further subjected to secondary screening using MSM broth having varying concentrations of Thiamethoxam (10, 50, 100 ppm). This was analyzed qualitatively using UV- spectrophotometer. The results confirm that selected six nitrogen-fixing isolates (CY18, CY11, CY13, CA10, CKA23 and CKU40) possessed dual functionality, maintaining nitrogen fixation while degrading pesticide residues. These isolates showed tolerance in primary screening and increase in bacterial OD during secondary screening which indicated some stochastic hydrolytic and oxidative reactions occurred to degrade thiamethoxam. Thus, study underscores the potential of native diazotrophs as sustainable bioremediation agents capable of mitigating pesticide contamination and could help in climate resilience by reducing greenhouse gases emission.
Key words: Thiamethoxam, greenhouse gas, pesticide degradation, nitrogen fixing bacteria, soil