Enhanced Cypermethrin Degradation Kinetics and Metabolic Pathway in Bacillus thuringiensis Strain SG4

Abstract

Cypermethrin is popularly used as an insecticide in households and agricultural fields, resulting in serious environmental contamination. Rapid and effective techniques that minimize or remove insecticidal residues from the environment are urgently required. However, the currently available cypermethrin-degrading bacterial strains are suboptimal. We aimed to characterize the kinetics and metabolic pathway of highly efficient cypermethrin-degrading Bacillus thuringiensis strain SG4. Strain SG4 effectively degraded cypermethrin under different conditions. The maximum degradation was observed at 32 °C, pH 7.0, and a shaking speed of 110 rpm, and about 80% of the initial dose of cypermethrin (50 mg·L−1) was degraded in minimal salt medium within 15 days. SG4 cells immobilized with sodium alginate provided a higher degradation rate (85.0%) and lower half-life (t1/2) of 5.3 days compared to the 52.9 days of the control. Bioaugmentation of cypermethrin-contaminated soil slurry with strain SG4 significantly enhanced its biodegradation (83.3%). Analysis of the degradation products led to identification of nine metabolites of cypermethrin, which revealed that cypermethrin could be degraded first by cleavage of its ester bond, followed by degradation of the benzene ring, and subsequent metabolism. A new degradation pathway for cypermethrin was proposed based on analysis of the metabolites. We investigated the active role of B. thuringiensis strain SG4 in cypermethrin degradation under various conditions that could be applied in large-scale pollutant treatment.

Kinetics and New Mechanism of Azoxystrobin Biodegradation by an Ochrobactrum anthropi Strain SH14

“…However, interestingly during this study, strain SH14 quickly adapted to the field conditions without any other treatment. Half-life of azoxystrobin in non-sterilized soils was also significantly shorter than in sterilized soils, indicating that the indigenous soil microorganisms had a synergistic effect on degradation ability of strain SH14.Similar results were observed in previous studies [43,44,[79][80][81][82]. O. anthropi is a widespread bacterium in natural habitats and has broad catabolic abilities, and it is capable of degrading various xenobiotic compounds including chlorate, cyhalothrin, cypermethrin, etc.…”

Insights Into the Biodegradation of Lindane (γ-Hexachlorocyclohexane) Using a Microbial System

“…The bacterial degradation of lindane and other xenobiotics are widely reported (Chen et al, 2012(Chen et al, , 2013Yang et al, 2018;Zhang H. et al, 2018;Bhatt et al, 2020c). Bacterial cells use organic pollutants as a sole source of carbon and nitrogen (Chen et al, 2011(Chen et al, , 2014Zhan et al, 2018b;Lin et al, 2020).…”

Bacilli-Mediated Degradation of Xenobiotic Compounds and Heavy Metals

“…Due to their wide range of applications in agriculture fields, they have been spread into soil and water and create environmental problems because of their toxic nature (Zhan et al, 2020 ). Many Bacilli have been isolated and characterized for the degradation of several pyrethroids (Chen et al, 2012b ; Cycoń and Piotrowska-Seget, 2016 ; Bhatt et al, 2020 ). In this section, Bacilli -mediated degradation of various pyrethroids is discussed.…”