Fecal strains Enterococcus mundtii from wild ruminants, their safety and postbiotic potential

Roe and red deers represent inhabitants in European forests but also in agricultural areas. In general, microbiota can have a significant impact on health. E. g. the genus Enterococcus was detected in more or less high abundance percentage in feces of red deers. To preserve negative impact of some microbiota, beneficial autochthonous strains can be selected for this purpose. The aim of this study was to assess safety, postbiotic activity and character of the fecal strains Enterococcus mundtii from roe and red deers living in Poland to spread basic microbiology research in this field and to select application candidate. Taxonomy of seven E. mundtii was determined using MALDI-TOF mass spectrometry and 16S rRNA sequence analysis. The evaluation score responded mostly with secure genus identification/probable species identification. Strains showed identity up to 100% with the sequence MK414812.1 of E. mundtii in GenBank. They were deoxyribonuclease and gelatinase- negative, with low-grade biofilm formation (0.100 ± 0.31 to 0.181 ± 0.43). E. mundtii were susceptible to antibiotics without production of damaging enzymes. They were absent of virulence factors genes (gelE, agg, esp, efaAfm, efaAfs). Postbiotic potential of the bacteriocin substance produced by E. mundtii revealed inhibition of indicator strains growth up to 48%. The most active substance was from the strain EM 1/90/2; inhibitory activity against enterococci, staphylococci and listeriae up to 86% (up to 1600 AU mL) was noted. The substance from the strain EM 6/123/1 reached inhibitory activity up to 81% with activity up to 400 AU/mL. It remained active at -20 ˚C for one month. E. mundtii were assessed with no and/or low- grade virulence factor rate and with postbiotic potential for further studies.