Construction of Pseudomonas aeruginosa ku gene deletion mutant and its effects on antibiotic resistance of biofilm

Abstract:

[Background] Pseudomonas aeruginosa is a common opportunistic pathogen, most of them can form biofilms which show the characteristics of high mutation rate and strong antibiotic resistance. Non-homologous end joining (NHEJ) is one of the major DNA double-strand break repair pathway which leads to DNA mutations. [Objective] To study the effects of NHEJ on biofilm-forming ability, mutation rate and drug resistance within biofilm in P. aeruginosa. [Methods] The ku gene deletion mutant strain Δku was constructed by in-frame deletion and its complementary strain was also obtained. We studied the biofilm-forming ability of each strain as well as the mutation rate and drug resistance within their biofilms. The transcription level of ku gene in P. aeruginosa biofilm was determined by qPCR. [Results] Compared with the wild-type strain, the ku gene deletion strain did not show significant difference in biofilm-forming ability but displayed a slight reduction in mutation rate and minimum inhibitory concentration (MIC) to ciprofloxacin and gentamicin within biofilms. The qPCR results showed that the transcription level of the ku gene was increased when biofilms were formed. [Conclusion] NHEJ affects the mutation rate and antibiotic resistance of P. aeruginosa biofilm. This study will provide a basis for exploiting the mechanisms of antibiotic resistance in P. aeruginosa.

Key words:Pseudomonas aeruginosa, Antibiotic resistance, Gene mutation, ku gene, Non-homologous end joining (NHEJ), Biofilm