Antibacterial Activity of Two Newly Isolated Bdellovibrio bacteriovorus Strains on Salmonella enterica Serovars of Food Safety Concern

Authors: AJAO, YEWANDE - Orise Fellow; Hiott, Lari; WILLIAMS, LAURA - Georgia Institute Of Technology; Jackson, Charlene; Frye, Jonathan

Submitted to: Microbiology Spectrum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2025
Publication Date: 9/15/2025
Citation: Ajao, Y., Hiott, L.M., Williams, L.E., Jackson, C.R., Frye, J.G. 2025. Antibacterial Activity of Two Newly Isolated Bdellovibrio bacteriovorus Strains on Salmonella enterica Serovars of Food Safety Concern. Microbiology Spectrum. 13. https://doi.org/10.1128/spectrum.00861-25.
DOI: https://doi.org/10.1128/spectrum.00861-25

Interpretive Summary: Salmonella continues to be the number one foodborne bacterial pathogen causing more than 1.3 million infections in the U.S. each year. To address this problem other bacteria can be used to control Salmonella when used as a probiotic. Bdellovibrio are obligate predators and have been described as living antibiotics since their predatory lifestyle enables them to kill pathogenic bacteria, making Bdellovibrio a promising biological control agent. Bdellovibrio strains were isolated from sampling sites in an urban watershed and tested for their killing activity on Salmonella enterica strains associated with human infections. To isolate Bdellovibrio from surface water samples from local tributaries to the Oconee River, an enrichment technique was used employing Salmonella Infantis as the prey bait. The isolated Bdellovibrio strains were sequenced; their prey range activity was tested against a panel of clinically significant S. enterica serovars, while predation efficiency was tested on S. Infantis. The result demonstrated the ability of two newly isolated periplasmic Bdellovibrio bacteriovorus strains, B. bacteriovorus YOA24 and B. bacteriovorus YOA38, to kill 11 antibiotic-resistant S. enterica serovars and effectively reduce S. Infantis populations. The strains were identified as periplasmic Bdellovibrio and members of the B. bacteriovorus based on phenotypic, microscopic, and genotypic characterization. B. bacteriovorus YOA 24 and YOA38 demonstrated the ability to reduce S. Infantis by 2 Logs in 24 h. The killing activity of B. bacteriovorus YOA24 and YOA38 indicates their potential to manage Salmonella outbreaks. Therefore, B. bacteriovorus strains YOA24 and YOA38 can be considered for development as therapeutic agents or probiotics against Salmonella.

Technical Abstract: Bdellovibrio are obligate predators and have been described as living antibiotics since their predatory lifestyle enables them to kill pathogenic bacteria, making Bdellovibrio a promising biological control agent. Bdellovibrio strains were isolated from sampling sites in an urban watershed and tested for their killing activity on Salmonella enterica strains associated with human infections. To isolate Bdellovibrio from surface water samples from local tributaries to the Oconee River, an enrichment technique was used employing Salmonella Infantis as the prey bait. The isolated Bdellovibrio strains were sequenced; their prey range activity was tested against a panel of clinically significant S. enterica serovars, while predation efficiency was tested on S. Infantis. The result demonstrated the ability of two newly isolated periplasmic Bdellovibrio bacteriovorus strains, B. bacteriovorus YOA24 and B. bacteriovorus YOA38, to kill 11 antibiotic-resistant S. enterica serovars and effectively reduce S. Infantis populations. The strains were identified as periplasmic Bdellovibrio and members of the B. bacteriovorus based on phenotypic, microscopic, and genotypic characterization. B. bacteriovorus YOA 24 and YOA38 demonstrated the ability to reduce S. Infantis by 2 Logs in 24 h. The killing activity of B. bacteriovorus YOA24 and YOA38 indicates their potential to manage Salmonella outbreaks. Therefore, B. bacteriovorus strains YOA24 and YOA38 can be considered for development as therapeutic agents or probiotics against Salmonella.