Abstract
Persistent use of permethrin has resulted in its ubiquitous presence as a contaminant in surface streams and soils, yet little is known about the kinetics and metabolic behaviors of this pesticide. In this study, a novel bacterial strain Acinetobacter baumannii ZH-14 utilizing permethrin via partial hydrolysis pathways was isolated from sewage sludge. Response surface methodology based on Box-Behnken design of cultural conditions was used for optimization resulting in 100% degradation of permethrin (50 mg·L−1) within 72 h. Strain ZH-14 degraded permethrin up to a concentration of 800 mg·L−1. Biodegradation kinetics analysis indicated that permethrin degradation by this strain was concentration dependent, with a maximum specific degradation rate, half-saturation constant, and inhibition constant of 0.0454 h−1, 4.7912 mg·L−1, and 367.2165 mg·L−1, respectively. High-performance liquid chromatography and gas chromatography-mass spectrometry identified 3-phenoxybenzenemethanol and 3-phenoxybenzaldehyde as the major intermediate metabolites of the permethrin degradation pathway. Bioaugmentation of permethrin-contaminated soils with strain ZH-14 significantly enhanced degradation, and over 85% of permethrin was degraded within 9 days with the degradation process following the first-order kinetic model. In addition to degradation of permethrin, strain ZH-14 was capable of degrading a large range of synthetic pyrethroids such as deltamethrin, bifenthrin, fenpropathrin, cyhalothrin, and beta-cypermethrin which are also widely used pesticides with environmental contamination problems, suggesting the promising potentials of A. baumannii ZH-14 in bioremediation of pyrethroid-contaminated terrestrial and aquatic environments.
Highlights
Synthetic pyrethroids (SPs) are the chemical analogs of pyrethrins, which are natural compounds extracted from the flowers of Chrysanthemum cinerariaefolium (Cyconand Piotrowska-Seget, 2016)
As the result of enrichment and isolation, one isolate designated as ZH-14 utilizing permethrin as the sole source of carbon and energy was selected for further study
The optimum temperature for growth is 30◦C, able to grow at 40◦C, pH range for growth is 5–10, could grow with 0–5% NaCl in Luria-Bertani medium (LB) broth
Summary
Synthetic pyrethroids (SPs) are the chemical analogs of pyrethrins, which are natural compounds extracted from the flowers of Chrysanthemum cinerariaefolium (Cyconand Piotrowska-Seget, 2016). The extensive use of these compounds in a wide variety of fields has resulted in widespread contamination of the Catabolism of Permethrin environment that is of ecological concern (Cyconand Piotrowska-Seget, 2016). Increasing evidence indicated that SPs may negatively affect non-target organisms, for instance, SPs are enormously toxic to aquatic organisms and bees (Tu et al, 2016), some SPs are harmful to the nervous system, immune system, and endocrine system of human beings (Ratelle et al, 2015). The increasing use of permethrin may pose great risks to terrestrial and aquatic environments as well as public health
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