The Genetic Mechanism of Resistance to Antibiotics in Bacillus pumilus 3-19 Strain

Abstract

Treatment of bacterial infections becomes increasingly complicated due to the emergence of bacterial resistance to antimicrobial agents. Until now, most studies on bacterial antibiotic resistance have focused mainly on clinically relevant isolates pathogenic microorganisms and lactic acid bacteria. Very limited information on the antimicrobial susceptibility profiles of Bacillus spp. is available. In this paper, we used Bacillus pumilus 3-19 strain, a derivative of a wild B. pumilus 7P strain that has acquired resistance to streptomycin. Comparative analysis of genomes showed that B. pumilus 3-19 became resistant to streptomycine due to a mutation in 56 codon of the rpsL gene (S12 protein of 30S ribosomal subunit) that resulted in the replacement of lysine with asparagine in the binding site of streptomycin. Bioinformatic analysis of rpoB gene (β-subunit of RNA polymerase) showed that there is also a point mutation in 185 codon, which can lead to rifampicin resistance. Nevertheless, B. pumilus 3-19 strain remained sensitive to rifampicin in disc diffusion assay.