APPARENT THERMAL-RESISTANCE OF BACILLUS-STEAROTHERMOPHILUS SPORES RECOVERED UNDER ANAEROBIC CONDITIONS

The effect of recovering Bacillus stearothermophilus spores under anae robic conditions on their apparent thermal resistance was studied. Spo res were suspended in bidistilled water as a reference medium, heated at 115, 117, 119, 121, 123 and 125 degrees C and recovered under aerob ic and anaerobic conditions. D values (decimal reduction time) obtaine d following recovery under anaerobic conditions were lower than those obtained under aerobic conditions. Reductions of between 31 and 48% we re found for all the temperatures studied. When spores were suspended in mushroom extract and recovered under anaerobic conditions the appar ent heat resistance was much lower than that obtained under aerobic co nditions (D-121 degrees C was 4.3 min and 1.7 min, under aerobic and a naerobic conditions, respectively). Heating the spores in mushroom ext ract and recovering the spores under anaerobic conditions produced an additive effect, decreasing the apparent heat resistance of the B. ste arothermophilus spores.