The release of dipicolinic acid during heating and its relation to the heat destruction of Bacillus stearothermophilus spores.

The rates of dipicolinic acid (Dpa) release and the rates of death were studied for spores of five strains of Bacillus stearothermophilus. It was observed that a highly significant relationship exists between the rate of Dpa release and rate of spore death for the four out of five strains tested and for all test temperatures. At 115 degrees C the rate of Dpa release was found to be faster than the rate of death, equal at 120 degrees C and slower at 125 degrees C. The role of Dpa in heat resistance was considered and a theory is proposed to explain the mechanism by which the heat resistance of bacterial spores is overcome.