RpoS involvement and requirement for exogenous nutrient for osmotically induced cross protection in Vibrio vulnificus

Abstract

Vibrio vulnificus is an opportunistic human pathogen which is the causative agent of food-borne disease and wound infections. V. vulnificus is able to adapt to a variety of potentially stressful environmental changes, such as osmotic, nutrient, and temperature variations in estuarine environments, as well as oxidative, osmotic, and acidity differences following infection of a human host. After exposure to sub-lethal levels of a particular environmental stress, many bacteria become resistant to unrelated stresses, a phenomenon termed cross protection. In this study, we examined the ability of osmotic shock to cross protect V. vulnificus to high temperature as well as oxidative stress. Log phase cells of V. vulnificus strain C7184o were cross protected by prior osmotic shock to both heat and oxidative challenge, but only when exogenous nutrient was present during the osmotic upshift. Further, and unlike other bacteria, nutrient starvation alone did not result in cross protection against either stress. When small amounts of nutrient were present during osmotic shock, cross protection to an otherwise lethal heat challenge developed extremely rapidly, with significant protection seen within 10 min. Cross protection to oxidative stress was slower to develop, requiring several hours. Although stationary phase alone conferred some cross protection to heat and oxidative stress, the alternate sigma factor RpoS was required for complete cross protection of log phase cells to oxidative stress but not for resistance to heat challenge. Together these findings suggest that the cross protective response in V. vulnificus is complex and appears to involve multiple mechanisms.

Shape and evolution of the fundamental niche in marine Vibrio

“…These results indicate that salinity and temperature tolerance mechanisms may be coupled at the molecular level, consistent with the findings of previous studies demonstrating that pre-exposure to osmotic stress increased the tolerance to heat stress in V. vulnificus (Rosche et al, 2005). Such coupling may result from temperature and salinity responses using common molecular pathways such as the SOS response pathway, the heat-shock response pathway and the general stress response pathway (Hengge-Aronis, 2002;Diez-Gonzalez and Kuruc, 2009).…”

“…Such coupling may result from temperature and salinity responses using common molecular pathways such as the SOS response pathway, the heat-shock response pathway and the general stress response pathway (Hengge-Aronis, 2002;Diez-Gonzalez and Kuruc, 2009). However, Rosche et al (2005) have demonstrated that the cross-protection between osmolarity and heat in V. vulnificus is independent of rpoS, the master regulator of the general stress response mechanism, and were unable to elucidate the origin of this cross-protection. An alternative potential mechanism for coupling between stress responses is partitioning of cellular resources between different stress response pathways.…”

Vibrio vulnificus: Disease and Pathogenesis

“…However, exposure to a slightly acidic pH prior to low-pH exposure dramatically increases survival of this organism, demonstrating the induction of a stress response(s) which provides a protective effect for the subsequent stresses (127). While there are limited data on protection against acid stress in this organism, nutrient starvation has been shown to induce cross-protective effects against oxidative stress (130). Furthermore, cross-protection following starvation has been shown to increase survival of this pathogen under both clinical and environmental conditions (9,130).…”

“…While there are limited data on protection against acid stress in this organism, nutrient starvation has been shown to induce cross-protective effects against oxidative stress (130). Furthermore, cross-protection following starvation has been shown to increase survival of this pathogen under both clinical and environmental conditions (9,130). These cross-protective abilities are likely an important contributor to the survival of this organism and may work in concert with the mechanisms outlined above to allow its survival as it passes through the gastric environment.…”

Alternative Sigma Factor RpoE Is Important for Vibrio parahaemolyticus Cell Envelope Stress Response and Intestinal Colonization

“…The stress response sigma factor, RpoS, has been studied in V. cholerae, V. vulnificus, V. anguillarum, V. harveyi, and V. alginolyticus and has been shown to be involved in a number of stress responses in these species, including starvation, osmolarity, ethanol, hydrogen peroxide, and acid stress responses (11)(12)(13)(14)(15)(16)(17). Previously, RpoS was also studied in V. parahaemolyticus and was found to play a limited role in the stress response in this organism (10).…”