Preparation of bacterial agent based on Bacillus subtilis BSF01 and its biodegradation effect on beta-cypermethrin

Objective  To prepare a bacterial agent that is able to degrade beta-cypermethrin (β-CP).

Method  Based on previously isolated and cultured Bacillus subtilis BSF01 which had excellent potential in rapidly degrading β-CP, the bacterial formulation was determined by optimizing additives and dosage. The degrading ability of prepared bacterial agent was evaluated in β-CP-contaminated soil under laboratory conditions.

Result  The optimal formulation was determined to blend 30% bacterial powder with 5% sodium dodecyl benzene sulfonate as wetting agent, 7% acacia gum as dispersant and 4% potassium phosphate as stabilizer, appending kaolin as the carrier to 100%. The quality assessment verified that the spore intensity of prepared bacterial agent reached 6.50×10¹¹ cfu·g^–1 with low water content (≤0.6%), high fineness (≥99%), short wetting time (32 s) and 78% suspensibility. The prepared agent was sprayed on β-CP-contaminated soil by diluting to 100, 1 000 and 2 000 times, respectively. After five days, about 87.50% of residual β-CP in soil was degraded by bacterial agent at 100-fold dilution, which rapidly decreased the residual level of β-CP in soil.

Conclusion  The prepared β-CP bacterial agent exhibits outstanding potential in realistic application with further optimization, which may provide an effective, safe and promising bacterial product for eliminating pyrethroid contamination in agricultural environment.