EFFECTS OF CARBON DIOXIDE ON THE GROWTH OF STREPTOCOCCUS BOVIS IN THE PRESENCE OF VARIOUS AMINO ACIDS

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Abstract
Effects of various amino acids on growth of 2 strains of S. bovis were studied by the in dividual addition of 22 amino acids to the basal medium containing only L-arginine HC1 as a source of amino N. Nine amino acids either in hibited or retarded growth, while 10 others stimulated growth to vary ing degrees. All of the observed inhibitions were reversed by addition of adequate levels of CO2 to the medium. Canavanine and homoarginine, which inhibit arginine metabolism in a number of other microorganisms, fail to inhibit growth of S. bovis in the presence of added CO2. The previously reported absolute requirement of these 2 strains for CO2 is a function of the growth phase; actively multiplying cultures do not require an exogenous source of CO2.