Synergistic role of abiotic factors driving viable but non‐culturable Vibrio cholerae

Abstract

SummaryVibrio cholerae O1, a natural inhabitant of estuarine environments, is found in a dormant, viable but non‐culturable (VBNC) state during interepidemic periods. Although the individual roles of abiotic factors affecting VBNC formation have been extensively studied, their interplay in driving this phenomenon remains largely unaddressed. Here, we identified that major abiotic factors synergize with low nutrient conditions governing entry of cells into the VBNC state. Specifically, V. cholerae cells exposed to a combination of alkaline pH and high salinity under aeration at low temperatures (VBNC‐inducing conditions) synergize to facilitate rapid entry into VBNC, whereas the opposite conditions prevented entry into the state. The major virulence regulator ToxR, and the stringent response protein RelA played opposing roles, repressing and facilitating VBNC entry respectively. Further, VBNC‐inducing conditions negated the effects of ToxR and RelA, facilitating rapid formation of VBNC cells. In summary, this study highlights the synergy between critical abiotic factors and identified ToxR and RelA as two associated regulators, allowing for the persistence of V. cholerae in aquatic environments. Insights obtained in this study will help better understand environmental survival non‐sporulating bacteria and transmission of facultative bacterial pathogens.

Cholera dynamics: lessons from an epidemic

“…Weather patterns and changes in the environment affected the spread of cholera in several ways. For instance, certain environmental abiotic variables such as the temperature, salinity and pH of aquatic ecosystems foster the proliferation and survival of V. cholerae, thus increasing the likelihood of cholera infections in humans [73,74]. Rain associated with changes in weather patterns can have significant effects on V. cholerae populations, as it increases the discharge of rivers into the ocean carrying terrestrial nutrients that enhance the growth and persistence of the bacterium [75,76].…”

“…For instance, certain environmental abiotic variables such as the temperature, salinity and pH of aquatic ecosystems foster the proliferation and survival of V. cholerae , thus increasing the likelihood of cholera infections in humans [73, 74]. Rain associated with changes in weather patterns can have significant effects on V.…”

Current Perspectives on Viable but Non-culturable Bacteria in Food Safety and Public Health

“…Due to the presence of a vast diversity of VBNC bacterial species, regulatory strategies are suggested to be strain-specific. Several studies uncovered the involvement of different mechanisms in VBNC induction, including RelA promotion and ToxR reduction in V. cholera (23), RpoS, MarA, YgfA, RelE (24), VapC, and HipA upregulation, and VapB downregulation in E. coli (25), and ClpP accumulation in Legionella pneumophila (26). In stress conditions, Campylobacter jejuni encodes hightemperature response protein B, polyphosphate kinase (PPK), and GltD and GlnA, which encode the required proteins for glutamine and glutamate production (27).…”

OCURRENCIA Y DISTRIBUCIÓN DE Vibrio cholerae CULTIVABLE EN LA CIÉNAGA GRANDE DE SANTA MARTA, CARIBE COLOMBIANO

“…Cabe resaltar que la no detección de V. cholerae por métodos de cultivo convencionales no asegura la ausencia de este patógeno potencial, puesto que, aunque en condiciones ambientales como baja concentración de nutrientes, alta salinidad y bajas temperaturas se limita su proliferación en ecosistemas acuáticos, esta bacteria puede permanecer en un estado de latencia conocido como viable no cultivable (VBNC) en el cual se mantiene hasta que las condiciones sean favorables para su crecimiento (Jesudason et al, 2000;Lutz et al, 2013;Jayakumar et al, 2020;Kopprio et al, 2020).…”