Action of Bacteriophage on Mixed Strain Cultures

Certain observed instances in which bacteriophage action could not be circumvented by the rotation of cultures in the manufacture of cottage cheese suggested to the writer that the mixed strain cultures used, though different in origin, contained similar strains of lactic streptococci.Deane and Nelson (1952) made a somewhat related observation: that some bacteria-free filtrates from cultured dairy products prepared with different commercial cultures lysed the same organisms.This study was made to establish whether various commercial cultures contain bacterial strains with similar bacteriophage sensitivity patterns.A whey activity test was used experimentally for studying the selection and rotation of cultures.