Beneficial Properties of Enterococcus faecium Strains Isolated From Bats' Fecal Samples

The principal objective of current study was to isolate and characterize Enterococcus faecium (E. faecium) strains from the fecal samples of Nyctalus noctula bats and to evaluate their probiotic potential and antimicrobial properties. Fecal samples were collected from bats in a rehabilitation center, and bacterial isolates were screened for antimicrobial activity against Listeria monocytogenes. Two bacteriocin-producing strains, E. faecium ST01TL and ST76TL, were selected based on rep-PCR fingerprinting and 16S rRNA sequencing. The proteinaceous nature of their antimicrobial substances was confirmed through protease treatment. These bacteriocins remained active under various pH, temperature, and chemical conditions. Both strains demonstrate high hydrophobicity, enzymatic activity with potential beneficial properties, and absence of hemolytic or mucin degradation activity. Molecular analyses revealed that studied strains carried genes for bacteriocin and GABA synthesis. However, some limited virulence traits or hazardous antibiotic resistance profiles were detected for both strains, a fact that merits additional attention and deeper investigations. Moreover, E. faecium ST01TL and ST76TL from bat feces possess general desirable probiotic traits and stable antimicrobial activity, suggesting their potential use in food safety and gut health improvement. These findings highlight bats as a novel source of probiotic strains with nutritional relevance. Further, in vivo studies, deeper safety assessments based on whole genome sequence analysis, and functional food applications are warranted to explore their full health-promoting potential.