Induction of SOS like responses by nitrofurantoin in Vibrio cholerae el tor cells

Differences in stress response after UVC or UVA irradiation in Vibrio parahaemolyticus

The SOS response is a global regulatory network for repairing DNA damage induced by various environmental stresses such as UV irradiation. The Escherichia coli SOS response has been extensively studied. However, there are no reports on the SOS response in Vibrio parahaemolyticus. In this study, we examined the SOS response in V. parahaemolyticus and compared the differential expression of genes induced by UVC and UVA irradiation. In UVC-exposed wild-type cells, expression of several DNA repair genes was increased. However, expression of these genes was not increased in ΔrecA or lexA mutants. Cell filamentation was observed in wild-type cells, but not in ΔrecA and lexA mutant cells. Sensitivity to UVC was significantly increased in ΔrecA, lexA mutant and Δlon strains compared with wild type. In the case of UVA irradiation, LexA-controlled DNA repair genes were minimally induced and cell filamentation was not observed. Sensitivity to UVA was the same in the mutant and wild-type strains. These findings suggest that there is a RecA-LexA-mediated SOS response in V. parahaemolyticus, and that this response is important to UVC tolerance but does not contribute to UVA tolerance.

Lipopolysaccharides of Vibrio cholerae

An account of our up to date knowledge of the genetics of biosynthesis of Vibrio cholerae lipopolysaccharide (LPS) is presented in this review. While not much information is available in the literature on the genetics of biosynthesis of lipid A of V. cholerae, the available information on the characteristics and proposed functions of the corepolysaccharide (core-PS) biosynthetic genes is discussed. The genetic organizations encoding the O-antigen polysaccharides (O-PS) of V. cholerae of serogroups O1 and O139, the disease causing ones, have been described along with the putative functions of the different constituent genes. The O-PS biosynthetic genes of some non-O1, non-O139 serogroups, particularly the serogroups O37 and O22, and their putative functions have also been discussed briefly. In view of the importance of the serogroup O139, the origination of the O139 strain and the possible donor of the corresponding O-PS gene cluster have been analyzed with a view to having knowledge of (i) the mode of evolution of different serogroups and (ii) the possible emergence of pathogenic strain(s) belonging to non-O1, non-O139 serogroups. The unsolved problems in this area of research and their probable impact on the production of an effective cholera vaccine have been outlined in conclusion.