Open AccessThe role of rpoS gene and quorum‐sensing system in ofloxacin tolerance in Pseudomonas aeruginosa
Author(s) -
Kayama Shizuo,
Murakami Keiji,
Ono Tsuneko,
Ushimaru Makiko,
Yamamoto Akitake,
Hirota Katsuhiko,
Miyake Yoichiro
Publication year - 2009
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2009.01717.x
Subject(s) - rpos , quorum sensing , ofloxacin , pseudomonas aeruginosa , microbiology and biotechnology , mutant , multidrug tolerance , biology , strain (injury) , antibiotics , gene , bacteria , biofilm , genetics , gene expression , virulence , ciprofloxacin , promoter , anatomy
The basis of the bactericidal action of antibiotics and the mechanisms of antibiotic tolerance are largely unknown. To elucidate one of the mechanisms of antibiotic tolerance, the present study investigated the role of Pseudomonas aeruginosa quorum sensing (QS) and the rpoS gene in antibiotic tolerance. The survival rates of the lasR and lasI mutants were observed to be lower than that of the parental strain in time‐dependent killing studies with 8 μg mL −1 ofloxacin, but the survival rates of the rhlR and rhlI mutants were not different from that of the parental strain. Moreover, a lasR ‐overexpressing strain was more tolerant to ofloxacin than the parental strain, but this was not the case for an rhlR ‐overexpressing strain. The mRNA expression levels of lasR , lasI , and rpoS in the wild‐type strain in the presence of bactericidal concentration of ofloxacin were lower than that in the absence of ofloxacin. In addition, the significant loss of antibiotic tolerance in the lasR mutant was recovered by the overexpression of rpoS . These results suggest that the Las QS system in P. aeruginosa is involved in the development of ofloxacin tolerance, and the tolerance induced by the Las‐system is regulated by rpoS gene.