Abstract
The spread of antibiotics and antibiotic-resistant bacteria in aquatic environments has become a major problem all over the world, and preventing the proliferation of resistant bacteria is one of the foremost concerns for global health. To achieve effective prevention, it is important to analyze antibiotic resistance genes and their expression mechanisms. Pseudomonas aeruginosa is a ubiquitous environmental gram-negative bacterium that adapts rapidly to antibiotic-contaminated environments, and harbors many unknown resistance-related genes in its genome. To identify new antibiotic resistance-related genes, randomly-sheared 8380 strain chromosomal DNA fragments were introduced into 8380 cells by using pUCP24. DNA fragments containing the scfB gene conferred resistance to various antibiotics and the resistant profile was similar to that of NfxC-type mutants expressing the MexEF-OprN efflux pump in an MexT-dependent manner. Wild-type 8380 cells did not express MexEF-OprN due to inhibition of MexT by active MexS. Since 8380 cells with introduction of the scfB gene expressed the MexEF-OprN efflux pump, but 8380?mexT cells with introduction of this gene did not, it was demonstrated that scfB induced the MexEF-OprN efflux pump in an MexT-dependent manner. Moreover, overexpression of scfF, a homologue of scfB, induced MexEF-OprN expression. These results suggest that the genome of P. aeruginosa contains many unknown resistance-related genes.
