Antimicrobial activity and safety of use of Enterococcus faecium PC4.1 isolated from Mongol yogurt

Screening of lactic acid bacteria strains isolated from Mongolian yogurt (Tarag) led to the isolation of Enterococcus faecium PC4.1 with a bacteriocin-like activity against Listeria genus and fungi. The antimicrobial substances in cell free supernatant were sensitive to proteolytic enzymes, while neither acidic conditions nor high temperature affected their activities. These antimicrobial substances were active after storage at 4 °C, −20 °C and −80 °C for over one month. The mode of action was determined as bactericidal. In the aim of further use of E. faecium PC4.1 as a biopreservative, the isolate was tested for resistance against antibiotics and for harboring virulence determinants. E. faecium PC4.1 was characterized as free from virulence factors, has low resistance to gentamicin and ampicillin but is susceptible to vancomycin.

► Enterococcus faecium PC4.1 lactic acid bacteria was isolated from Mongolian yogurt. ► It displayed bacteriocin-like activity against Listeria genus and fungi. ► The antimicrobial substances in supernatant were sensitive to proteolytic enzymes. ► E. faecium PC4.1 has no virulence factors and has low resistance to antibiotics. ► It is a good candidate as a biopreservative.