Isolation and characterization of chlorpyrifos-degrading bacteria in tea-growing soils

The excess use of pesticides in the agricultural sector has caused environmental pollution and affected the complete ecosystem. Among the various commonly used pesticides, chlorpyrifos (CPF) is widely used against multiple agrarian pests due to its effectiveness and higher insecticidal activities. However, along with its beneficial usage, CPF has various residual effects on the environment, causing multiple negative impacts on aquatic organisms and human health. Consequently, methods for eliminating CPF in the background are essential. Among the currently available approaches to CPF remediation, biological methods using microorganisms are eco-friendly and cost-effective. Therefore, this study was conducted to isolate and characterize chlorpyrifos-degrading bacteria from the tea-growing soil of Vietnam. For this, soil samples were collected from the 20 tea-growing areas of Vietnam. From the collected samples, three bacterial strains viz., Methylobacterium populi CNN2, Ensifer adhaerens VNN3, and Acinetobacter pittii CNN4 have been isolated by using streak plate method and identified based on 16S rRNA gene analysis. The study results showed that under laboratory conditions, E. adhaerens VNN3 had the highest CPF degradation ability and was followed by the strain M. populi CNN2. In liquid medium, CPF concentration (100 mg/L) was reduced by 95.2% and 81.4% by E.adhaerens VNN3 and M. populi CNN2, respectively, after 72 h. Further, under in-vitro conditions, the concentration of CPF was reduced from 500 mg/kg to 112 ± 1.73 (77.6%) and 197 ± 2.08 mg/kg (60.6%) by E. adhaerens VNN3 and M. populi CNN2, respectively. Based on the obtained results, it can be concluded that E. adhaerens VNN3 and M. populi CNN2 can be used for CPF-contaminated agricultural soil remediation.