Bioremediation of fipronil using Bacillus sp. FA3: Mechanism, kinetics and resource recovery potential from contaminated environments

Abstract Present study investigates the role of Bacillus sp. FA3 in fipronil degradation and resource recovery from a contaminated environment. The degradation conditions of fipronil with strain FA3 were optimized using Box-Behnken design at a temperature of 32 °C, a pH of 7.0, and a shaking speed of 110 rpm. Strain FA3 efficiently metabolized fipronil in mineral salt medium (MSM) and degradation was 76.0%, in 15 days. The degradation kinetics of fipronil revealed effective degradation in the presence of strain FA3, with a kinetic parameters, half-life (t1/2), degradation constant (k), and determination coefficient (R2) of 7.7 days, 0.891 day−1, and 0.921, respectively. Maximum specific degradation rate (qmax), half-saturation constant (Ks), and inhibition constant (Ki) for fipronil were 1.4155 day−1, 65.1 mg L−1, and 156.3 mg L−1, respectively. FA3 cells immobilized with sodium alginate and an agar disc significantly enhanced fipronil degradation as compared to unimmobilized culture. FA3 strain could be helpful in biodegradation of fipronil and resource recovery from the wastewater and soil system. Based on the effective degradation rate and kinetics under in vitro conditions, this strain could be used for large-scale treatment of fipronil contaminants in soil and water environments.