Purpose Aquatic bacteria of the genus Vibrio include animal and human pathogens. The occurrence of Vibrio-related diseases has been associated with the current climate change-driven increase of sea surface temperature. Vibrio spp. can enter into the viable but non-culturable (VBNC) state, as a consequence of starvation in seawater at low temperatures. In such physiological state, Vibrio cells are no longer culturable on standard media agar plates but can resuscitate if incubated at 30 °C prior to plating, retaining virulence. Since limited information is available on regards to this topic, in this work, we characterized the phenotypic changes of four Vibrio spp. strains (one laboratory strain and three environmental isolates) in cold seawater microcosms, investigating the relationship between resuscitation and a hydrogen peroxide-induced oxidative stress. Methods Cell phenotypic changes and the effect of hydrogen peroxide and/or catalase addition to the medium were studied on VBNC and resuscitated cells by flow cytometry in microcosm experiments, paralleled by culturability experiments by plating. Results The cells of all the Vibrio strains changed their phenotype upon the induction of the VBNC state resulting in cell dwarfing and decrease in DNA quantity, losing the ability to grow on solid media. These features were partially or totally reverted when the cells were treated for resuscitation. Hydrogen peroxide at concentrations as low as 0.007 mM prevented resuscitation and a prolonged exposure to hydrogen peroxide at concentrations far under those inhibiting the growth of log-phase cells permanently damaged VBNC cells, which could not be resuscitated. However, the potential of culturability of VBNC cells could be preserved, at least for a part of the population, by plating the cells in the presence of catalase. The study also showed that during the resuscitation process, the cells gradually increased their resistance to hydrogen peroxide. Conclusions The timing and mode of induction of the VBNC state, as well as cell resuscitation and response to hydrogen peroxide, differed among Vibrio strains, indicating that induction and resuscitation from dormancy could vary in the context of species belonging to a single genus.
|Original language||English (US)|
|Journal||Annals of Microbiology|
|State||Published - Jan 4 2023|
Bibliographical noteKAUST Repository Item: Exported on 2023-01-06
Acknowledged KAUST grant number(s): 2018-OSR-CRG 2018-3739
Acknowledgements: The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 311975 (MACUMBA). The publication reflects the views only of the authors, and the European Union cannot be held responsible for any use which may be made of the information contained therein. DD has been supported by the King Abdullah University of Science and Technology Competitive Research Grant Program 2018-OSR-CRG 2018-3739. Authors kindly thank Prof. Raffaella Di Cagno for providing V. campbellii BAA-1117™ strain.