A New Enterococcus hirae Strain Exhibits Antibacterial Activity against Vancomycin-Resistant Enterococci

The antibacterial activity of a new Enterococcus hirae strain Y7 isolated from a soil against three pathogenic Enterococcus species is reported. The new strain identified by the next-generation sequencing method was cultured according to conventional microbiological standards. Antibacterial activity was assessed using agar spot and agar well diffusion assays against Enterococcus hirae ATCC 10541, vancomycin-resistant enterococci (VRE): Enterococcus faecium ATCC 700221 and Enterococcus faecalis ATCC 51299. All tested pathogenic indicator bacteria were susceptible to this new E. hirae strain Y7, as well as against its cell-free supernatant (CFS), and the protein-containing fraction of CFS. Additionally, minimum bactericidal concentrations of the CFS protein-containing fraction were detected as 60 µg/mL for E. hirae ATCC 10541 and E. faecium ATCC 700221, and 500 µg/mL for E. faecalis ATCC 51299. According to the results, this E. hirae strain Y7 seems to be a new source of alternative antibacterial peptides, especially for VRE enterococci, and possibly other bacteria.