Physiological and Nutritional Features of Corynebacterium pyogenes

Abstract

Growth and acid metabolic products were similar when Corynebacterium pyogenes was grown aerobically or anaerobically in a serum-free medium (SFM). This indicated that C. pyogenes obtains energy for growth primarily by fermentative metabolism even under aerobic growth conditions. Growth yield was reduced by 90% in SFM minus glucose, 50% in SFM minus NaHC03, 90% in SFM minus yeast extract, 100% in SFM minus Trypticase and yeast extract, and 30% in SFM minus haemin or Trypticase. Growth was not detectable when a known mixture of amino acids, vitamins, and nucleic acid bases were substituted for Trypticase and yeast extract in SFM; addition to the latter medium of a peptide source such as Trypticase or casitone supported good growth of the organism. When NaHCO, was omitted from SFM and dissolved COz in the medium was rigorously excluded, growth was undetectable indicating that C. pyogenes has an obligate requirement for CO, for growth. Succinate, formate and acetate were the major fermentation products in SFM, whereas in SFM minus HCO, or haemin, lactate was the major product and only small quantities of other acids accumulated.