Proteolytic Enterococcus faecalis isolates produced strong inhibitory activity against mutans streptococci in a deferred antagonism test on Columbia agar base medium supplemented with 5% human blood. Hematin was responsible for this inhibitory effect and its formation by the enterococci was dependent upon incubation in the presence of hemoglobin under conditions favourable to protease production.
26 endocervical lactobacilli were subdivided into 6 groups according to their patterns of sensitivity (S‐types) to the bacteriocin‐like inhibitory agents produced by a set of 6 streptococcal strains of Lancefield groups A, B, G and F. Further differentiation of the lactobacilli was achieved by assessing their sensitivity to bacteriocin‐producing strains of Streptococcus salivarius, group C streptococcus. Streptococcus uberis, Streptococcus mutans and Enterococcus faecalis. Some of the anti‐lactobacillus activity of E. faecalis ssp. liquefaciens strain T142 was shown to be due to its proteolytic digestion of hemoglobin in the blood‐containing test medium with formation of inhibitory levels of hematin. It is suggested that the combined production of bacteriocins and hematin by proteolytic enterococci could afford them a competitive growth advantage over some indigenous lactobacilli in the vaginal milieu at the time of menses.
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