Predator-prey interactions between Halobacteriovorax and pathogenic Vibrio parahaemolyticus strains: geographical considerations and influence of Vibrio hemolysins

Authors: Richards, Gary; Watson, Michael; WILLIAMS, HENRY - Florida A & M University; JONES, JESSICA - Us Food & Drug Administration (FDA)

Submitted to: Microbiology Spectrum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2023
Publication Date: 7/6/2023
Citation: Richards, G.P., Watson, M.A., Williams, H.N., Jones, J.L. 2023. Predator-prey interactions between Halobacteriovorax and pathogenic Vibrio parahaemolyticus strains: geographical considerations and influence of Vibrio hemolysins. Microbiology Spectrum. 11(4). https://doi.org/10.1128/spectrum.02353-23.
DOI: https://doi.org/10.1128/spectrum.02353-23

Interpretive Summary: Vibrio parahaemolyticus are common marine bacteria and formidable obstacles to seafood safety. Strains causing disease in humans are numerous and difficult to control, especially within oysters and other seafoods eaten raw or lightly cooked. A predatory bacterium known as Halobacteriovorax is also found in the marine environment and is capable of attacking and killing V. parahaemolyticus. This study evaluated 4 strains of Halobacteriovorax that we isolated from seawater from Hawaii, the coast of Alabama (Gulf Coast), and the Delaware Bay (Mid-Atlantic) to determine if they would infect 23 different strains of V. parahaemolyticus that were isolated from sick individuals from around the U.S. All four strains of Halobacteriovorax readily attacked and killed 21 of the 23 Vibrio strains, regardless of where the Halobacteriovorax and vibrios originated from. The two remaining vibrios were killed, one by the Hawaiian strain and the other by the Gulf strain of Halobacteriovorax. Consequently, it appears that the four Halobacteriovorax used in this study would be useful tools for the development of new processing technologies to kill disease-causing vibrios in oysters and other seafoods.

Technical Abstract: Halobacteriovorax is a genus of naturally occurring marine predatory bacteria that preferentially attack, replicate within, and lyse vibrios and other bacteria. This study evaluated the specificity of four Halobacteriovorax strains against important sequence types (STs) of clinically relevant Vibrio parahaemolyticus, including pandemic strains ST3 and ST36. The Halobacteriovorax were previously isolated from seawater from the Mid-Atlantic, Gulf of Mexico, and Hawaiian coasts of the United States. Specificity screening was performed using a double agar plaque assay technique on 23 well-characterized and genomically sequenced V. parahaemolyticus strains isolated from infected individuals from widely varying geographic locations within the U.S. With few exceptions, results showed that Halobacteriovorax were excellent predators of the V. parahaemolyticus strains regardless of the origins of the predator or prey. Sequence types and serotypes of V. parahaemolyticus did not influence host specificity, nor did the presence or absence of genes for the thermostable direct hemolysin (TDH) or the TDH-related hemolysin, although fainter (cloudy) plaques were present when one or both hemolysins were absent in three of the Vibrio strains. Plaque sizes varied depending on both the Halobacteriovorax and Vibrio strains evaluated suggesting differences in Halobacteriovorax replication and/or growth rates. The very broad infectivity of Halobacteriovorax toward pathogenic strains of V. parahaemolyticus make Halobacteriovorax a strong candidate for use in commercial processing applications to enhance the safety of seafoods.