Ligilactobacillus murinus Strains Isolated from Mice Intestinal Tract: Molecular Characterization and Antagonistic Activity against Food-Borne Pathogens

Abstract

Considering the objectives of “One Health” and the Sustainable development Goals “Goodhealth and well-being” for the development of effective strategies to apply against bacterial resistance,food safety dangers, and zoonosis risks, this project explored the isolation and identification ofLactobacillus strains from the intestinal tract of recently weaned mice; as well as the assessment ofantibacterial activity against clinical and zoonotic pathogens. For molecular identification, 16SrRNA gene-specific primers were used and, via BLAST-NCBI, 16 Ligilactobacillus murinus, oneLigilactobacillus animalis, and one Streptococcus salivarius strains were identified and registered inGenBank after the confirmation of their identity percentage and the phylogenetic analysis of the16 Ligilactobacillus murinus strains and their association with Ligilactobacillus animalis. The 18 isolatedstrains showed antibacterial activity during agar diffusion tests against Listeria monocytogenes ATCC15313, enteropathogenic Escherichia coli O103, and Campylobacter jejuni ATCC 49943. Electrophoreticand zymographic techniques confirmed the presence of bacteriolytic bands with a relative molecularmass of 107 kDa and another of 24 kDa in Ligilactobacillus murinus strains. UPLC-MS analysis allowedthe identification of a 107 kDa lytic protein as an N-acetylmuramoyl-L-amidase involved in cytolysisand considered a bacteriolytic enzyme with antimicrobial activity. The 24 kDa band displayedsimilarity with a portion of protein with aminopeptidase function. It is expected that these findingswill impact the search for new strains and their metabolites with antibacterial activity as an alternativestrategy to inhibit pathogens associated with major health risks that help your solution.