Cypermethrin bioremediation in presence of heavy metals by a novel heavy metal tolerant strain, Bacillus sp. AKD1

Abstract

An isolate, designated as Bacillus sp. AKD1, based on the 16S rRNA gene sequence, could transform 86% ± 3.6% of cypermethrin (initial concentration of 100 ppm) in 7 days, but biotransformation was inhibited at concentrations above 150 ppm. As determined by the Response Surface Methodology (RSM), optimum parameters for the biotransformation were: pH value of 8.0, temperature of 37.8 °C and inoculum density of 4.4 mg ml−1 (wet wt.). Glucose, fructose and glycerol inhibited insecticide biotransformation at concentrations above 0.5%, 1.0% and 0.5 respectively (w/v). Minimum inhibitory concentrations of Bacillus sp. AKD1 for Co2+, Cr6+, Cu2+, Fe2+, Li+, Ni2+, pb2+, V5+ and Zn2+ were 0.2 mM, 1.4 mM, 1.8 mM, 5.1 mM, 7.8 mM, 2.9 mM, 0.6 mM, 8.2 mM, and 0.6 mM respectively. At concentrations less than the MIC, V5+ and Fe2+ did not affect cypermethrin biotransformation, but Li+ was found to be inhibitory above 4.0 mM. The results obtained in this study have significant importance in the development of bioremediation strategy for removal of cypermethrin in cypermethrin contaminated areas co-contaminated with heavy metals.