Sustainable Approach in Bioremediation of Chlorpyrifos, and Its Metabolites Using Bacillus paramycoides, Isolated From a Paddy Leaf Surface

In the current study, we present two main components: (1) A detailed survey based on a structured questionnaire answered by farmers of Purba Medinipur district of West Bengal, India, and (2) the bioremediation of chlorpyrifos and its metabolite 3,5,6-trichloro-2-pyridinol (TCP) by Bacillus paramycoides. The survey findings indicated that out of 51 reported pesticides, herbicides were most commonly used (76%), with 9% classified as carcinogenic. Notably, 65% respondents reported health-related issues connected to pesticide use. We isolated a bacterium from paddy leaves, identified as B. paramycoides through 16S rRNA gene sequencing. In controlled batch assays, this bacterium effectively degraded chlorpyrifos (at a concentration of 120 mg/L) by 83.08% within 9 days under stationary conditions at a temperature of 35°C ± 2°C and pH 7.5 in M9 minimal medium. Additionally, TCP, a persistent and toxic metabolite of chlorpyrifos, was degraded by approximately 50% over 12 days of treatment. Both chlorpyrifos and TCP demonstrated statistically significant efficacy concerning the duration of microbial treatment (p < 0.05). Further, pot experiments involving Vigna radiata (mung beans) indicated enhanced seedling growth when amended with the degraded products of chlorpyrifos and TCP. This mineralization process contributed to better plant growth compared to the control and those treated solely with pesticides. Biocompatibility assessments in fish erythrocytes showed that the hemolysis caused by chlorpyrifos was significantly reduced when treated with the bacterium. These findings suggest the potential application of B. paramycoides in soil amendment for the detoxification and mineralization of chlorpyrifos, ultimately enhancing soil fertility.