Observations on the Acetate and Citrate Metabolism of Streptococcus Lactis and Streptococcus Cremoris

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Abstract
A completely synthetic medium (Henderson and Snell, J. Biol. Chem. 172: 15 1948) containing either 10 mg/ml of citrate, 10 mg/ml of acetate or none of either was used to study the acetate-citrate metab-olism of Streptococcus lactis and S. cremoris. Cultures were grown in litmus milk and inoculated into the test media at a rate of 0.05% and incubated for a period of 24 hours at 32[degree]C. This was followed by 2 serial transfers in the test media, with identical inoculation rates, incubation times, and temperatures; growth was determined turbidimetrically. The strains were placed in 2 groups (for statistical analysis) on the basis of their reactions in maltose medium and the presence or absence of growth at 40[degree]C. Statistical analysis of the data shows that the group of organisms that utilize maltose and grow at 40[degree]C (S. lactis) responds significantly to citrate; they fail to show a significant response to acetate. The group of organisms that fail to utilize maltose and do not grow at 40[degree]C (S. cremoris) gives a significant response to acetate, but does not respond significantly to citrate; some strains are inhibited by this level of citrate. In the absence of Ca pantothenate, none of the cultures can grow in the presence of acetate or citrate. Co-enzyme A, as a source of pantothenate is considerably less effective in meeting this requirement than is Ca pantothenate.

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