Influence of oxyR on Growth, Biofilm Formation, and Mobility of Vibrio parahaemolyticus

Abstract

Vibrio parahaemolyticus is a common marine food-borne enteropathogen. In this study, we examined the antioxidative activity, growth, biofilm formation, and cell mobility of an oxyR deletion mutant and its genetically complementary strain of V. parahaemolyticus. oxyR is the regulator of catalase and ahpC genes. Protection against extrinsic H 2 O 2 and against the organic peroxides cumene hydroperoxide and tert-butyl hydroperoxide was weaker in the deletion mutant than in its parent strain. Expression of the major functional antioxidative genes, ahpC1 and VPA1418, was markedly decreased in the oxyR mutant. Growth of this mutant on agar medium was significantly inhibited by autoclaved 0.25% glucose and by 0.25% dipotassium hydrogen phosphate, 0.5% monosaccharides (glucose, galactose, xylose, and arabinose), or 114.8 mM phosphates. The inhibition of the growth of this oxyR mutant by extrinsic peroxides, autoclaved sugars, and phosphates was eliminated by the complementary oxyR gene or by the addition of catalase to the autoclaved medium, while no inhibition of growth was observed when filter-sterilized sugars were used. The formation of biofilm and swimming mobility were significantly inhibited in the oxyR mutant relative to that in the wild-type strain. This investigation demonstrates the antioxidative function of oxyR in V. parahaemolyticus and its possible roles in biofilm formation, cell mobility, and the protection of growth in heated rich medium. Vibrio parahaemolyticus is a halophilic Gram-negative bacterium that is commonly associated with food-borne gastroenteritis (1), and it has exhibited global significance since the occurrence of pandemic O3:K6 strains in 1996 (2).The incomplete reduction of oxygen during aerobic metabolism or by exposure to metals, redox-active chemicals, or some environmental stresses produces various reactive oxygen species (ROS) in bacteria (3-5). ROS can damage all cellular components, including protein, DNA, and membrane lipids (6, 7). Therefore, antioxidative activity is required by pathogenic bacteria for their successful growth and survival under environmental stresses and is sometimes associated with their virulence (8), whereas characteristic antioxidative functions have been demonstrated in V. parahaemolyticus (9, 10).Several common antioxidative factors are used to scavenge ROS, including superoxide dismutases (SOD), catalases, and alkyl hydroperoxide reductase subunit C's (AhpC) (11). The expressions of catalase and ahpC genes are usually regulated by OxyR (12), which is a redox-sensitive transcriptional regulator of the LysR family in Escherichia coli, Salmonella spp., and other bacteria (13-17). OxyR also participates in pathogenesis by promoting biofilm formation, fimbrial expression, and mucosal colonization in pathogenic bacteria (18); nevertheless, the mechanism of oxidative stress defense in these phenomena is not clear (19).The function of oxyR has been examined in a few Vibrio species but not in V. parahaemolyticus. The effect of oxyR on the survival of bacteria a...

KatE From the Bacterial Plant Pathogen Ralstonia solanacearum Is a Monofunctional Catalase Controlled by HrpG That Plays a Major Role in Bacterial Survival to Hydrogen Peroxide

“…In addition, the katE mutant strain did not show reduced ability to produce biofilms, another important trait for the wilting disease development ( Figure 4 ). Biofilm-growing cells usually experience endogenous oxidative stress and many antioxidant systems were shown to be induced under this growth condition ( Resch et al, 2005 ; Ram et al, 2005 ; Mikkelsen et al, 2007 ; Shanks et al, 2007 ; Chung et al, 2016 ). In fact, the role of catalase and superoxide dismutase in the development of mature biofilms was previously demonstrated in X. citri subsp.…”

Non‐redundant expression of the two katG genes in Vibrio parahaemolyticus V110

“…Deletion of oxyR in V. parahaemolyticus leads to a growth defect in the sugar‐rich media and impaires its biofilm formation and motility. Moreover, OxyR mediates the induction of katE (VPA1418) and aphC1 (VPA1683) by cumene . In this study, we found that loss of oxyR led to a weakened induction of katG1 and katG2 by oxidative stress, but it did not completely abolish the activation of two genes.…”

“…In V. paraheamolyticus , OxyR is required for the induction of katE1 (VPA1418) and aphC1 (VPA1683) by cumene. It is also positively associated with the growth in heated rich medium, biofilm formation and motility . RpoS plays roles in the environmental survival, acid stress resistance, and the regulation of a virulence factor PrtA .…”

Contribution of OxyR Towards Differential Sensitivity to Antioxidants inXanthomonas oryzaepathovarsoryzaeandoryzicola

“…Loss of OxyR was previously reported to affect the growth of several species of bacteria (Chung et al 2015;Maciver and Hansen 1996;Vinckx et al 2008). In our study, the growth of oxyR deletion mutants of X. oryzae pvs.…”