Effects of carbon dioxide on the growth and amino acid metabolism of Streptococcus bovis.

The position of Streptococcus bovis among the Lacobactriacae is of interest because of the extremely simple nitrogen requirements of this organism in contrast with the other streptococci which have been investigated. Niven, Washburn, and White (1948) studied the nutritive requirements of fifteen strains of S. bovis and found that all but two grew in a medium containing arginine as the sole source of amino nitrogen. Further investigation of the metabolic patterns of one strain of S. bovis led Washburn and Niven (1948) to report several interesting amino acid antagonisms in the metabolism of this organism when it was grown in a medium in which arginine supplied the nitrogen requirement. During the course of some experiments on amino acid metabolism in two strains of S. boi, the present authors found that growth in a medium similar to that of Washburn and Niven was often poor and irregular, and a considerable difference between duplicate tubes was frequently observed. The use of younger, heavier inocula resulted in somewhat improved growth. The better results with the heavy inocula suggested the possibility that carbon dioxide was involved in the growth of S. bovis in such media since heavy inocula are likely to contain significant amounts of metabolic CO2. In order to determine whether this were true, an investigation of the role of CO2 in the growth of S. bovis was undertaken.