234. Bacteriophage-organism relationships in the group of lactic streptococci

Abstract

The methods used for isolation and purification of bacteriophages active against lactic streptococci are described. An account is given of the relationships between nine apparently distinct phage races and eleven strains of lactic streptococci. The phages show a tendency towards strain specificity but there are some races which attack up to four different strains. Resistant strains usually arise on continued incubation of lysed cultures. Cross-resistance tests, in those cases where two or more phages act on one strain of streptococci, indicate that the relationships between the phages do not follow any simple rule.