Growth Dynamics of selected Vibrio spp. in mono-, co-culture and multi-bacterial microcosms: Investigating the prevalence of Vibrio parahaemolyticus in seawater

Abstract

We examined the growth dynamics and interspecific competition of six environmental Vibrio isolates (V. parahaemolyticus, V. vulnificus, V. cholerae, V. mimicus, V. cincinnatiensis, and V. zhanjiangensis) recovered from Malaysian seawater. Monoculture assays were conducted across temperature (25–37°C), salinity (0.3–40 ppt), and nutrient (0.001X–0.05X Marine Broth or MB equivalent strength) gradients, followed by co-culture and multi-bacterial microcosm experiments (at 31°C, 26 ppt, 0.01X MB). Regression analyses showed no significant positive response to increasing temperature, whereas tested species responded positively to increasing salinity. Responses to nutrient enrichment suggested that V. parahaemolyticus, V. mimicus and V. vulnificus exhibited r-strategy framework, whereas V. zhanjiangensis represented K-strategy. In contrast, V. cholerae and V. cincinnatiensis could not be clearly classified. In co-culture and multi-bacterial microcosms, V. parahaemolyticus consistently outcompeted both Vibrio and non-Vibrio competitors, even when introduced at lower initial abundance. Therefore, the ecological success of V. parahaemolyticus in these systems was not solely determined by intrinsic growth capacity or environmental suitability, but also by interspecific dynamics. The frequent involvement of V. parahaemolyticus in aquaculture disease outbreaks may be driven by previously underappreciated interspecific competitive advantages that enable it to outcompete other microbes.