Grouping of lactic streptococci by gel electrophoresis of soluble cell extracts.

Soluble cell proteins obtained from 35 strains of lactic streptococci were examined by gel electrophoresis. A mathematical analysis of the densitometer scans of the gels enabled strains to be grouped according to their overall similarity. Strains which were known to be variants of the same parent strain fell into the same group, supporting the validity of the method. It is suggested that strains which are alike according to their gel electrophoretic patterns when grown under standard conditions have an overall phenotypic similarity and that this indicates a similarity in genotype. The relevance of this to selection of strains of lactic streptococci for cheesemaking is discussed.