Isolation and preliminary characterization of Streptococcus cremoris (strain 202) bacteriocin

Ability to produce bacteriocin (lactostrepcin) is demonstrated in Streptococcus cremoris. However, lactostrepcin was found to be produced by only one strain (strain 202) out of the 17 S. cremoris strains tested. This bacteriocin is preliminarily characterized, it differs from other lactic streptococci bacteriocins. The strain 202 bacteriocin acts on many strains of lactic streptococci, strains of Bacillus cereus, and some strains of Leuconostoc and Lactobacillus. It was shown that strain 202 contains some plasmids, but we were not able by preliminary observations to prove the plasmid localization of the determinant(s) for lactostrepcin production by this strain. In persistent lactostrepcin-negative variants of strain 202, in comparison with the parental strain, the plasmid pattern may be changed or unchanged.