Exploring the potential of algae-bacteria interactions in the biocontrol of the marine pathogen Vibrio parahaemolyticus

The marine bacterium Vibrio parahaemolyticus is the leading cause of seafood-related food poisoning worldwide and a pathogen of marine species harvested in aquaculture. An outbreak of pathogenic V. parahaemolyticus within crustacean and bi-valve aquaculture facilities often results in significant loss of farmed product and in the spread of the pathogen into the human population. Evidence shows several marine bacteria and microalgae species have antibacterial effects against marine pathogens, including V. parahaemolyticus. This study explored the potential of combining possible mutualistic species as a consortium to enhance antibacterial properties against V. parahaemolyticus. Marine bacteria and microalgae were screened with the aim of identifying those able to successfully coexist while demonstrating growth suppression of multiple V. parahaemolyticus strains. This trial involved four screening phases to find effective inhibitor species and to gain insight into species-specific influences on cell growth. The combination of Tetraselmis sp. and Pseudoalteromonas peptidolytica achieved the greatest inhibition rate of V. parahaemolyticus of all combinations. This pairing resulted in the significant reduction of up to 24 ± 15% in Vibrio sp. copy number mL⁻¹ day⁻¹ in two of the five examined V. parahaemolyticus strains within five days, compared to control cultures absent of probiotic bacteria. Applying probiotic consortia such as this has the potential for use as a biocontrol technique within mariculture, but it will require additional research into the self-sustainability of successful consortia in natural aquatic conditions.