INFLUENCE OF SPORULATION MEDIUM AND DIVALENT IONS ON THE HEAT-RESISTANCE OF ALICYCLOBACILLUS-ACIDOTERRESTRIS SPORES

The influence of divalent cations on the heat resistance of spores of the thermoacidophilic spoilage bacterium Alicyclobacillus acidoterrest ris was studied. The heat resistance of A. acidoterrestris spores was not affected by the presence of the different divalent cations (Ca2+, Mg2+, Ba2+, Mn2+ and Sr2+) in the sporulation medium, and by the demin eralization or remineralization. And the Ca and Mn contents in A. acid oterrestris spores were scarcely changed by these treatments. However, the heat resistance of Bacillus subtilis spores was affected with the changes of Ca content in the spores. The Ca contents in A. acidoterre stris spores of the different forms were greater than the DPA content. In contrast, the DPA content in the B. subtilis spores was greater th an the Ca content. These findings suggest that the presence of constan t amount of Ca-DPA and a stronger binding characteristic of divalent i ons, especially Ca and Mn, is reflected in the specific heat resistanc e of A. acidoterrestris spores.