[Changes in the cell wall composition and structure of Streptococcus pyogenes during batch culture].

Changes in S. pyogenes cells in the process of batch cultivation have been studied. The composition of S. pyogenes cell walls has been studied by amino acid analysis; besides, their resistance to enzymatic hydrolysis and the electric conductivity of cell-wall lysates have been determined at different phases of the growth of S. pyogenes. The molar amino acid composition, expressed in percent, is unrelated to the growth phase, while the content of amino acids in preparations changes in the process of growth and reaches its maximum in the middle and in the end of the logarithmic phase. At the same time the electric conductivity of cell-wall lysates reaches the minimum level at these growth stages. The authors suggest that additional electrically charged compositions are formed in the cell walls at the beginning of the logarithmic and stationary phases. A considerable increase in the initial rate of cell-wall lysis with muramidase has been found to occur at the end of the logarithmic phase. This difference in the initial rate in the initial rates of lysis of S. pyogenes cell walls at different growth phases decreases after previous treatment of the cell walls with streptolytin possessing proteolytic activity. Analysis of these data leads to a conclusion on the "loose" structure of the outer protein layer of the cell wall at the end of the logarithmic phase of the growth curve.