Biodegradation of Carbofuran and Paraquat by Indigenous Soil Microorganisms

Aim: It aimed at the biodegradation of Carbofuran and Paraquat using the active microbial population resident in a farmyard soil in the Federal University of Petroleum Resources (FUPRE), Ugbomoro Community, Delta State.

Study Design: Microcosms were set-up in triplicates; sampling for pesticides’ loss and microbial counts were done bi-weekly.

Place and Duration of Study: Study was done in Environmental Management and Toxicology Department, FUPRE and Chemistry Department, University of Benin between June 2019 and July 2019.

Methodology: Carbofuran and Paraquat were applied to farmyard soil containing active microbial population at recommended and four times the recommended doses. A sterile control was equally setup. Biodegradation was monitored with the High Performance Liquid Chromatography (HPLC). Microbial counts were monitored using standard methods.

Results: Carbofuran decreased from 108.6 ± 0.69 μg/kg (day 0) to 39.2 ± 3.8 μg/kg (day 28) and 301.4 ± 1.29 μg/kg (day 0) to 241.4 ± 2.83 μg/kg (day 28) for recommended and four times recommended rates, respectively. Also, there were complete removal of Paraquat in treatments with the recommended rate while it decreased from 268.3 ± 5.21μg/kg (day 0) to 144.4 ± 2.38 μg/kg (day 28) at four times the recommended rate. In the abiotic control, were little losses of both pesticides. Total heterotrophic bacterial, fungal and actinomycetes counts increased (day 14 to 21) in contaminated soils. Significant differences in degradation with respect to pesticides treatment and time were observed.

Conclusion: The microorganisms grew at different concentrations reducing both Carbofuran and Paraquat in contaminated soils. Their presence and high numbers confirmed that they are ubiquitous, diverse and can adjust to any harsh environment. Increased microbial counts showed that they grew in presence of the chemicals and degraded them. Thus, these indigenous microbial population can be used for the clean-up of these pesticides pollution in farms to improve such environment.