Differentially expressed outer membrane proteins of Vibrio alginolyticus in response to six types of antibiotics.

Vibrio alginolyticus is an opportunistic pathogen that occasionally causes life-threatening infections in individuals and results in great losses in marine aquacultures of crustaceans and fish. Recently, antibiotic-resistant strains of the bacterium from clinical and environmental sources have been reported with increasing frequency. However, few reports were involved in the antibiotic resistance of this bacterium at molecular levels. In the present study, Western blotting was utilized to investigate altered OM proteins of V. alginolyticus in response to six types of antibiotics: erythromycin, kanamycin, tetracycline, streptomycin, nalidixic acid, and chloromycetin. Seventeen OM proteins have been reported here for the first time to be related to antibiotic resistance. They were porins OmpU, OmpN, putative OmpU and LamB; transport proteins VA0802, VA2212 (FadL) and VPA0860; TolC family TolC and VA1631; lipoprotein VA0449; OmpA family VPA1186 and VA0764; iron-regulated proteins OmpV, VPA1435, and VA2602; and receptor protein OmpK; hypothetical protein VA1475. Importantly, VA2212 was up-regulated in response to the five antibiotics except nalidixic acid, and VPA1186 was down-regulated in response to the six antibiotics in antibiotic-stressed bacteria. They might be potentially universal targets for designing the new drugs that inhibit multi-resistant bacteria. These findings suggested that parallel investigations into a bacterium responding to several types of antibiotics would be helpful not only for the further understanding of antibiotic-resistant mechanisms but also for the screening of valuable targets of new drugs controlling antibiotic-resistant bacteria.