Screening and Genome Sequencing of Deltamethrin-Degrading Bacterium ZJ6.

Abstract

Deltamethrin is a pyrethroid insecticide with high insecticidal activity and a wide range of applications. However, with the increased amount and scope of its application, the accumulated toxicity of deltamethrin has gradually raised concerns. In this study, a bacterium strain, which used deltamethrin as its sole carbon source and was named ZJ6 (Lysinibacillus sp.-ZJ6), was isolated from soil samples collected from the sewage outlet of a pesticide plant in Tianjin. Based on morphological observations of ZJ6, as well as its physiological and biochemical characteristics and 16S rDNA sequence (Gen Bank Accession No. KU129013), the strain was identified as Lysinibacillus fusiformis sp.. A study of the degradation characteristics of ZJ6 revealed that the optimum conditions for shake flask fermentation to degrade deltamethrin by ZJ6 were as follows: pH 7.0, a temperature of 30°C, a substrate concentration of 100-200mg/L, an inoculation volume of 10%, and 7days culturing at 160rpm. Under these conditions, the degradation rate of deltamethrin by ZJ6 reached 57.2%. Preliminary sequencing of the ZJ6 genome showed that it has a total length of 3,921,852bp and contains 4567 genes. The average length of each gene in the ZJ6 genome is 859bp, and these genes account for 84.62% of the total genome length. KEGG metabolic pathway analysis revealed that genes involved in sugar metabolism and metabolism of exogenous chemical substances were significantly enriched in the genome of ZJ6. Comparison with the COG database showed that 2839 of the predicted protein sequences from the ZJ6 genome had COG numbers. Among all protein functions, the number of genes involved in general functions was the highest (372). For the first time, it was found that ZJ6 has relatively strong deltamethrin degradation ability and high value as a subject for further research. In addition, this study provides a reference to guide the preparation of pesticide-degrading bacterial agents and environmental remediation.