Bacteria intrinsic to Medicago sativa (alfalfa) reduce Salmonella enterica growth in planta

Abstract

Aims The purpose of this study was to determine whether plant-associated bacteria (PAB) can reduce Salmonella enterica colonization and infection of alfalfa sprouts to reduce the risk of foodborne illness. Methods We isolated plant associated bacteria from alfalfa seeds and sprouts. Monoclonal isolates of the bacteria were obtained and tested for their ability to inhibit Salmonella Typhimurium growth in alfalfa sprouts over 6-days. Genome sequencing and annotation was used to construct draft genomes of the bacteria isolated in this study using Illumina sequencing platform. Results We observed that a cocktail of five PAB could reduce Salmonella growth in alfalfa sprouts from ∼108 CFU g−1 to ∼105 CFU g−1, demonstrating a protective role. Genome sequencing revealed that these bacteria were members of the Pseudomonas, Pantoea, and Priestia genus, and did not possess genes that were pathogenic to plants or animals. Conclusions This work demonstrates that PAB can be utilized to reduce pathogen levels in fresh produce which may be synergistic with other technologies to improve the safety of sprouts and other fresh produce.

Bacillus strain BX77: a potential biocontrol agent for use against foodborne pathogens in alfalfa sprouts

“…Our results are in line with previous reports, which showed inhibition of S. enterica on sprouted seeds by nonspore-forming bacteria. For example, Vitt et al (2023) recently reported that plant-associated bacteria, including members of the Pseudomona and Pantoea genera, reduced Salmonella growth in alfalfa sprouts from ca. 10 8 to ca.…”

“…10 8 to ca. 10 5 CFU/g (Vitt et al, 2023). Liu and co-workers found that P. fluorescenes A506, a known biocontrol agent, inhibited the attachment of S. enterica and enterohemorrhagic E. coli strains to alfalfa seeds, as well as other vegetable seeds.…”

“…More recent studies have found that B. subtilis ATCC 6051 and B. mojavensis RRC 101 compete with Salmonella and E. coli for attachment to alfalfa seeds (Liu et al, 2021). Even more recently, Vitt et al (2023) reported that a Gram-positive strain of the genus Priestia isolated from alfalfa is capable of inhibiting the growth of Salmonella in sprouted alfalfa seeds (Vitt et al, 2023).…”