Predation enhances survival and growth of pathogenic and non-pathogenic isolates of Vibrio cholerae

Vibrio cholerae a major health problem in developing countries because of its ability to cause the disease cholera in humans. As V. cholerae bacteria are common inhabitants of temperate marine and brackish water environments worldwide, they are subject to intense top-down pressure by amoebae, which can affect their survival and replication in natural reservoirs. In these environments, interactions with amoebae, single celled eukaryotic predators of bacteria, are inevitable. This study examined the interactions between a model amoeboid predator, Acanthamoeba castellanii, and diverse strains of V. cholerae to better understand the adaptations of these bacteria to eukaryotic grazing pressure over 48 hours. Our analysis showed that V. cholerae TP (non-pathogenic GFP variant) and AR4100 (pathogenic GFP variant) increased growth (TP growth difference: 4.29-fold, AR4100 growth difference: 4.67- fold) when co-cultured with A. castellanii in comparison to E. coli co-culture, while SIO (non- pathogenic GFP variant) had no growth difference (SIO growth difference: -1.05-fold). In general, V. cholerae isolates induced cyst formation in amoebae within 48 hours and remained viable after ingestion. These findings suggest that complex predator-prey relations may ultimately impact the survival of strains of these potential pathogens in the environmental reservoirs in significantly different ways, changing the population structure of these organisms in their communities