Correlation of M protein production with those factors found to influence growth and substrate utilization of Streptococcus pyogenes.

In the absence of proteinase formation, factors reported to influence the growth or fermentation by streptococci have been evaluated to determine their quantitative effect upon the production of M protein during the growth of Streptococcus pyogenes. Buffers, amino acids, peptides, gross organic additions, and carbohydrate substrates were tested under a variety of cultural conditions. The M protein content was remarkably constant throughout the late logarithmic period of growth, i.e., when the cell population doubled, the M protein doubled. However, several factors affected the M protein content per milligram of cells (dry weight). When types 1, 12, and 22 were grown aerobically in a semidefined medium, the M protein content of the cell population essentially doubled; in Todd-Hewitt broth, this aerobic effect on M protein synthesis was not observed. When cells grown on Todd-Hewitt broth were transferred to medium containing 0.1% starch and no added glucose, the M protein content per milligram of cells (dry weight) increased as much as fourfold. When growth was initiated in glucose, the rate of M protein formation was at a maximum in the early logarithmic phase of growth and was comparatively greater than the rate of cellular multiplication. When the amount of substrate fermented was greater than 0.2%, increased M protein was not observed. An evaluation of the effects of medium or conditions of growth showed the units of M per milligram of cells (dry weight) were not influenced by a shift in the stoichiometry of either the anaerobic or aerobic fermentation, substrate used, or adenosine triphosphate utilized for growth. These results show that M protein synthesis is subject to limited glucose repression or substrate catabolite repression.