Abstract
Optimal growth temperatures in yeast extract broth for nine strains of Streptococcus cremoris, selected as representative of 45 strains, varied from 28 through 31 C and averaged 29.3 C. Maximal growth temperatures were 34.4 through 38.9 C in broth and in litmus milk, with an average of 36.1 C. The one strain of Streptococcus lactis had an optimal growth temperature of 31.5 C and a maximum of 42 C. Maximal growth temperatures for the nine strains of S. cremoris were 3.9 to 10.4 C above the optimal temperatures, and strains with high optimal temperatures did not have necessarily correspondingly high minimal or maximal temperatures. Only three strains with low maximal growth temperatures apparently were damaged by treatment for 90 min at 38.9 C.