Abstract

In this study, we incubated Vibrio parahaemolyticus and Vibrio alginolyticus (marine food-borne pathogens bacteria) in seawater for 8 months to study their morphologic, proteomic and genetic responses to starvation. The atomic force micrographs of stressed strains showed a reduction of the cells size and an evolution to two coccoid-shape forms whose length is less than 0.4 μm and between 0.5 and 1 μm. Extracellular protein patterns and gelatinase profiles of stressed bacteria were also altered. Indeed, these modifications were manifested by the appearance and/or disappearance of bands as well as in the level of expression of certain proteins. In addition, we also searched for the presence of eight Vibrio cholerae virulence genes: toxR, toxS, toxRS, ctxA, zot,ace, toxT, and Virulence Pathogenicity Island (VPI) in the genome of investigated strains. The expression level of VPI gene studied by reverse transcriptase polymerase chain reaction was decreased, whereas the mRNA quantities of toxR, toxS, and ace in starved Vibrio remained stable.

Key words: Vibrio, seawater, alterations, morphology, proteins secreted, virulence gene expression, RT-PCR