Antibacterial activity of enterococci strains against Vibrio cholerae

Thirty-seven strains of enterococci isolated from milk and milk products from Santa Fe (Argentina) region were tested for antagonistic activity against Vibrio cholerae 01 and non-01. Seven of 17 strains of Enterococcus faecalis, five of 10 strains of Enterococcus faecium and four of 10 strains of Enterococcus durans produced inhibition zones against the indicator species. The activity of the antibacterial compounds was completely destroyed by treatment with trypsin and pronase E in most cases (only the supernatant fluids of a few strains remained weakly active after the treatment), but was resistant to heat treatment at 100 degrees C during 10 and 30 min. When the 10-fold concentrated supernatant fluids were added to a fresh culture of sensitive cells it produced a rapid inactivation. According to these preliminary tests, different strains of enterococci produced compounds with slightly different antivibrio properties, and these compounds were heat-resistant and had a predominantly proteinaceous nature.