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Isolation of a novel beta-cypermethrin degrading strain Bacillus subtilis BSF01 and its biodegradation pathway

Xiao, Ying, Chen, Shaohua, Gao, Yuanqi, Hu, Wei, Hu, Meiying, Zhong, Guohua
Applied microbiology and biotechnology 2015 v.99 no.6 pp. 2849-2859
Bacillus subtilis, activated sludge, biodegradation, bioremediation, biotechnology, carbon, cyhalothrin, cypermethrin, deltamethrin, gas-chromatography-mass spectrometry, metabolites, microbiology, pH, pollution, response surface methodology
Continuous use of the pyrethroid insecticide beta-cypermethrin (beta-cp) has resulted in serious environmental contamination problems. We report here that a novel bacterial strain BSF01, which was isolated from activated sludge and identified as Bacillus subtilis (collection number: CCTCC AB 2014103), showed high efficiency in degrading beta-cp. Strain BSF01 was able to utilize beta-cp as the sole carbon source for growth and degraded 89.4 % of 50 mg L⁻¹ beta-cp within 7 days. The optimal conditions for beta-cp degradation were determined to be 34.5 °C, pH 6.7, and inocula amount 0.11 g dry wt L⁻¹ using response surface methodology. The kinetic parameters q ₘₐₓ, K ₛ, and K ᵢ were established to be 2.19 day⁻¹, 76.37 mg L⁻¹, and 54.14 mg L⁻¹, respectively. The critical inhibitor concentration was determined to be 64.30 mg L⁻¹. Seven metabolites were identified by gas chromatography–mass spectrometry. Furthermore, a novel biodegradation pathway for beta-cp was proposed on the basis of analysis of the metabolites. This strain was also capable of degrading a wide range of pyrethroid insecticides including cypermethrin, deltamethrin, cyhalothrin, and beta-cyfluthrin, which similar to beta-cp are hazardous chemicals. Taken together, our results depict the biodegradation pathway of beta-cp and highlight the promising potentials of strain BSF01 in bioremediation of pyrethroid-contaminated environments.