Effect of Environmental Conditions on Group a Streptococcal Pyrogenic ExotoxinProduction

摘要

The effect of various environmental conditions on the production of streptococcalpyrogenic exotoxins (SPES) was examined. The standard kinetics of SPE production in the strains T253 cured T12, 86-858, T18P, and NY-5 were established in order to determine the changes attributed to the experimental manipulations. SPE A was initially detected in mid log phase and production ceased as the culture entered stationary phase. SPE B was initially detected in late log phase and production continued into stationary phase. In experimentally manipulated environments (1% bacto-tryptone, high concentrations of glucose, and aerated conditions), the rate of SPE A production was apparently reduced, yet the final concentration achieved was unchanged. No effect upon SPE A production was observed in conditions of selected temperatures (250 C, 370 C, and 400 C), 7% carbon dioxide, and various pH ranges (pH 5.5 to 6.5, pH 6.8 to 7.2, and pH 7.6 to 8.5) . Except for the decrease in rate, SPE A production was generally not effected by any environmental manipulations. SPE B production was increased in 1% bacto-tryptone, and 7% carbon dioxide, while decreased in high glucose concentrations and aerated conditions. No effect on SPE B was observed at selected temperatures. Proteinase activity was examined in all strains. Three distinguishable types of proteolytic activity were observed, two of which appeared to be distinct from SPE B. The appearance of a clear zone of surrounded by an opaque ring (generally accepted as a positive result) was evident in fractions from both 86-858 and T18P after preparative isoelectric focusing (IEF). 713 cloned SPE B was also found to possess some proteinase activity.