Purification and chemical composition of an altered Rm-10 bacteriocin

Abstract

We attempted to isolate and purify a bacteriocin from Streptococcus mutans Rm-10 cells which have a stationary phase in the growth curve. The bactericidal substance was isolated from the supernatant fluid and purified by arginine Sepharose 4B, gel filtration, sucrose density gradient ultracentrifugation and lysine Sepharose 4 B. In SDS-PAGE analysis of the purified bacteriocin (N-ABC), only one band was recognized at a molecular weight of approximately 34 kDa, where antibacterial activity against the indicator strain was displayed. N-ABC was a protein-carbohydrate complex, and was found to be rich in the sugars glucose and rhamnose, and in the amino acids alanine and lysine. These results indicate that Streptococcus mutans Rm-10 used in this experiment produced a bacteriocin different from two previously reported bacteriocins.