Sensitivity of Spores to Hydrostatic Pressure: Mechanisms of Activation, Injury and Repair. Phase 1

Abstract : The sensitivity of spores Bacillus subtilis 168 a,id Clostridium sporogenes PA3679 to the effects of pressure (4,000 atmospheres) alone and in combination with nisin, temperature and pH were determined. The results showed that PA3679 spores were more resistant to nisin than B. subtilis 168 but were more sensitive to the combined effects of pressure, elevated temp. and reduced pH. Pressure oscillations of spores' suspensions did not result in a significant log10 reduction in spore count as compared to continuous pressurization. When spores of B. subtilis 168 and PA3679 were examined for sensitivity to pressure (4,000 atm.) in different buffers at pH 7.0 in the presence of food-grade salts, no significant difference was observed, relative to buffers. Sodium acetate (up to 5%) bad no adverse effect on the viability of spores of B. subtilis 168 and PA3679. However, B. subtilis 168 spores were less sensitivity to sodium nitrite (less than 5% caused no inhibition) than spores of PA3679 (0.02% caused inhibition). When spores of B. subtilis 168 and PA3679 were tested for sensitive to sucrose laurate, pressure and temperature, PA3679 was highly sensitive at 25C but B. subtilis was not. However, at 45C spores of PA3679 were equally sensitive to the combo. Inoculated pack studies revealed that when the combination of pressure (4,000 atm.), temp (55C) and risin (0.1 IU/mL) were used spores count (300,000 spores/pouch) was reduced by 3 log10.