Purpose: Alternative “green” technologies are needed to reduce pathogens, including antibiotic-resistant pathogens, in foods. One potential treatment involves the use of predatory bacteria of the genus Halobacteriovorax, which are gram-negative, motile, marine organisms which attack, infect, and kill other gram-negative bacteria.
Methods: We isolated from seawater Halobacteriovorax against several Vibrio parahaemolyticus strains, and against E. coli O157:H7, and Salmonella enterica serovar Typhimurium DT104 using modified plaque assays. Assays were performed on lawns of different pathogens to determine the ability of Halobacteriovorax to infect various host strains. Oysters and seawater were also challenged with a streptomycin-resistant strain of V. parahaemolyticus and their levels were monitored as Halobacteriovorax counts in natural seawater increased.
Results: Host specificity was narrow for Halobacteriovorax strains originally isolated in V. parahaemolyticus, but was broader for strains isolated in either E. coli or Salmonella Typhimurium. Halobacteriovorax significantly reduced (P<0.05) the levels of V. parahaemolyticus in seawater and oysters, indicating a potential use for Halobacteriovorax treatment in aquaculture and depuration settings.
Significance: Halobacteriovorax may be a practical substitute for antibiotics in reducing fish and shellfish pathogens in aquaculture, while isolates against E. coli and Salmonella spp. have the potential to reduce pathogens on the surface of meats, fruits and vegetables. Halobacteriovorax treatment by soaking or dipping represents a green technology which could easily and effectively reduce pathogens in foods and on their surfaces.