# Susceptibility to Postbiotic Substances-Enterocins of the Strains Enterococcus thailandicus from Beavers (Castor fiber)

## TL;DR

This study examines how postbiotic substances called enterocins affect Enterococcus thailandicus strains from beavers in Poland.

## Contribution

The study introduces postbiotic inhibition as a novel strategy for controlling E. thailandicus.

## Key findings

- Six E. thailandicus strains were susceptible to seven enterocins at up to 25,600 AU/mL.
- Two strains carried the gelE virulence gene but showed no strict pathogenic traits.
- Postbiotics from E. faecium and E. durans effectively inhibited E. thailandicus growth.

## Abstract

Eurasian beaver (Castor fiber) populations have been reintroduced to European countries, though this bears the risk of novel wildlife pathogen reservoir establishment. The species nova E. thailandicus was described first in Thailand as a food-derived strain. Later, this species was detected in the feces of pigs, poultry, sewage, and humans. In those studies, the potential risk posed by this species was evaluated. Against that background, the aim of this study was to investigate the susceptibility to postbiotic active substances (enterocins) against fecal E. thailandicus strains from beavers caught in Poland. The strains were identified with the use of 16S rRNA gene similarity sequencing. These six E. thailandicus strains with low-grade biofilm-forming abilities and two strains with the presence of the gelE virulence factor gene were susceptible to seven enterocins produced by non-autochthonous strains, mostly of the species E. faecium and E. durans. The inhibitory activity against the tested strains reached 25,600 AU/mL. Although the studied E. thailandicus strains did not show a strictly pathogenic character, their growth inhibition by postbiotics was identified as a novel elimination strategy.