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pubmed:abstractText |
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.
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