Sporulation and synthesis of extracellular proteinases in Bacillus subtilis are more temperature-sensitive than growth.

Bacillus subtilis 115 grew in a medium with amino acids and glucose with the maximum specific growth rates mu of 1.20-1.10/h in the temperature range of 45-48 degrees C. Activity of the extracellular neutral proteinase excreted by 1.3 mg/mL dry mass during 8 h of the postexponential and stationary growth phases decreased from its maximum value of 0.23 TU/mL at 40 degrees C to 0.13 and 0.06 TU/mL at 45 and 48 degrees C, respectively. Formation of the extracellular serine proteinase decreased even more - from 0.18 TU/mL at 40 degrees C to 0.06 and 0.03 TU/mL at 45 and 48 degrees C, respectively. Sporulation, expressed as the portion of sporangia with refractile spores at the 6th h of the stationary phase decreased from 46% at 40 degrees C to 17 and 3% at 45 and 48 degrees C, respectively.