Characterization and mode of action of a purified bacteriocin from the oral bacterium Streptococcus mutans RM-10.
The purified bacteriocin was sensitive to proteolytic enzymes such as trypsin, alpha-chymotrypsin and pronase, but resistant to papain and pepsin. Lowering the pH of the bacteriocin caused precipitation, and the Abs280 of the supernatant reached a minimum at pH 3.6, suggesting that this is the isoelectric point. Such a pH value coincides with minimum bacteriocin activity. The effect of the bacteriocin was bactericidal rather than bacteriolytic and concentration dependent. Treatment of Streptococcus faecalis ODU with Rm-10 bacteriocin led rapidly to the cessation of biosynthesis of macromolecules, DNA, RNA and protein. Electron microscopy showed bacteriocin fibres attached in aggregated bundles to target cells; after ultra-sonication or detergent treatment they were individually attached to the cell surface and, at the same time, the apparent bacteriocin activity had doubled. Bacteriocin activity was not altered by filter-sterilized saliva components. Oral rinsing with Rm-10 bacteriocin reduced the number of viable salivary bacteria after 20 min, suggesting a possible therapeutic use for Rm-10 bacteriocin.
D000818:Animals; D001419:Bacteria / Q000302:isolation & purification; D001430:Bacteriocins / Q000302:isolation & purification / Q000494:pharmacology*; D003902:Detergents / Q000494:pharmacology; D013293:Enterococcus faecalis / Q000378:metabolism; D004798:Enzymes / Q000494:pharmacology; D005502:Food; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D012463:Saliva / Q000382:microbiology; D013295:Streptococcus mutans / Q000378:metabolism*; D014465:Ultrasonics
D001430:Bacteriocins; D003902:Detergents; D004798:Enzymes