Heavy Metal Resistance and Its Related Mechanisms in Pseudomonas aeruginosa

Abstract

Abstract: It was to investigate the prevalence of heavy metals resistance in Pseudomonas aeruginosa clinical strains and study the related mechanisms. Measurement of bacterial growths in the medium with various heavy metals;construction of transcription fusion reporter gene for analyzing the expression level of the RND efflux pump CzcCBA;analysis of the regulatory gene czcRS with PCR method and sequence alignment. Results showed that among 158 clinical strains, the majority was able to thrive in the presence of 0.002 mol/L Co²⁺, 1 strains didn’t grow in the presence of 0.001 mol/L Co²⁺, and control strain ATCC27853 could tolerate 0.003 mol/L Co²⁺ during the incubation. Two clinical strains and strain ATCC 27853 were selected for other heavy metals tolerance analysis and the resistance profiles were similar to that of Co²⁺. To investigate the mechanisms of heavy metal resistance, the expression level of gene czcC was determined via detecting β-galactosidase activity encoded by the transcription fusion reporter gene czcC-lacZ. The results showed that β-galactosidase activity corresponded with their respective resistance to heavy metals and heavy metals could induce β-galactosidase activity increase in each strain. Two-component regulatory genes czcR and czcS of the czcCBA were amplified and their sequences were analyzed. Comparing with the genome of strain PAO1, regulator CzcR had the same sequence in all the three strains, while each regulator CzcS had multiple amino acids substitutions in each strain. Clinical strains of P. aeruginosa were resistant to heavy metals. The expression level of RND efflux pump czcCBA contributed to heavy metals resistance. Mutations in regulator CzcS might play key role in the expression variation of operon czcCBA.

Key words: Pseudomonas aeruginosa, Heavy metals resistence, RND efflux pump, CzcCBA, Two-component regulatory system czcRS

Li Qun, Yang Hongjiang, Lin Shuxiang, Wang Wei, Ye Yujie. Heavy Metal Resistance and Its Related Mechanisms in Pseudomonas aeruginosa[J]. Biotechnology Bulletin, 2013, 0(6): 160-166.

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