355. Cheese starter ‘recovery’ after attack by bacteriophage. (Strain dominance in multiplestrain starters)

Abstract

1. Three experimental starters were prepared by mixing three unrelated phaging strains ofStr. cremoris. The corresponding phages were used to determine whether changes occurred in the relative numbers of these strains on daily subculture.The results indicated that (a) in a multiple-strain starter one strain may overgrow the others and become responsible for most of the acid produced by that starter about 1 week after mixing the strains. The starter may soon become virtually a single-strain starter. (b) Even during the day's making, one of three strains, mixed together at the time of introduction into the cheese vat, may partly overgrow the other two strains, (c) The dominance of a particular strain in a starter mixture may be affected by the temperature of propagation.