CHAHAT SHARMA, POOJA SHARMA* AND RAJ SINGH
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: March 6, 2024; Accepted: April 12, 2024)
ABSTRACT
Despite the benefits, over use of pesticide has a negative impact on human health as residues transfer in food chain and ground water through leaching, percolation and bioaccumulation. To investigate the possibility of microbial degradation of hazardous chemicals in the natural environment, nitrogen-fixing bacteria isolated from wheat soil were employed. Nitrogen fixing bacterial isolates were identified using molecular technique 16SDNA sequencing. The isolates belonged to Bacillus subtilis species. These bacteria were initially grown in nitrogen free media (Burks media plates) having different concentration of cypermethrin (10, 25, 50, 75 and 100 ppm) after the primary screening of pesticide tolerance efficiency. Six chosen bacterial isolates, A10, KU40, KA23, Y18, Y11 and Y13 were used for further biodegradation studies using carbon nitrogen deficient media. Secondary screening was performed by growing them in different concentration (50 and 100 ppm) of cypermethrin in minimal salt media under the standard conditions (30oC, 7 pH; 120 rpm). Bacterial growth increased with gradual days and OD for maximum tolerant strain was recorded as 0.406 for KA23 at 600 nm on 10th day of degradation analysis. The percentage of degradation of cypermethrin was calculated by analyzing its residue in MSM at 280 nm using UV spectrophotometer. At 50 ppm of CP, three isolates (Y13, Y11 and KU40) showed complete degradation (99.9%) and other isolates (Y18, A10 and KA23) showed more than 90% of degradation after 10 days. At 100 ppm of CP, half of the conc. was reduced on 6th day (50%) and on 10th day, more than 80% of CP was degraded by all the nitrogen fixing bacterial isolates under shaking conditions. The active role of diazotrophs in cypermethrin degradation under various conditions was investigated which could be beneficial in large-scale pollutant treatment.
Key words: BPesticide, cypermethrin, nitrogen, bacteria, minimal salt media, diazotrophs