Purification of a Bacteriocin-like Inhibitor by Enterococcus faecium Strain 62-6 Antagonistic to the Growth of Vaginal Lactobacilli: Potential Significance for the Pathogenesis of Bacterial Vaginosis
Martin, Michael S.
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Bacterial vaginosis is a polymicrobial syndrome characterized by a shift in the ecology of the normal vaginal microflora. This includes a decline in both the prevalence and concentration of Lactobacillus populations that generally dominate the healthy microflora. The mechanism(s) by account for this are currently not well understood. Previous studies of this laboratory tested vaginal isolates of the genera of bacteria associated with the normal microflora for the ability to inhibit the growth of vaginal lactobacilli and discovered one strain, Enterococcus faecium 62-6, which exhibited strong activity. Sepharose cation-exchange chromatography, SOS and Native-PAGE analysis were used to isolate the protein. Gel overlayer assays were used to identify the inhibitor in the PAGE gels and indicated it was associated with a protein of approximately 10kDa in size. Samples with the 10kDa band correlated to Lactobacillus inhibition in well diffusion assays while samples without the band .exhibited no inhibitory activity. Native-PAGE assays were then used to isolate the 10kDa protein band, which was subsequently analyzed for amino acid composition. These results suggest the approximate amino acid composition of the inhibitor produced by E. faecium.