Controlling the Sporulation of Clostridium sporogenes and the Heat Resistance of the Spores

S ummary . During growth of Clostridium sporogenes in tryptone‐salt‐peptone‐glucose medium the pH value of the medium varies due to formation of acid and CO 2 and to subsequent production of NH 3 . Glucose concentrations of 0·2, 0·5 or 1·0% result in increasing sporulation times and in spores of low, extremely high ( D 110 c . 80 min) and negligible heat resistance, respectively. When the pH value is maintained at 7, a reproducible sporulation time of a few hours is observed and the resulting spores have a heat resistance ( D 110 ) of 13 min, regardless of the glucose concentration.