The Effect of Bioindicator Preparation and Storage on Thermal Resistance of Bacillus stearothermophilus Spores

Vessoni Penna, Thereza Christina
Ishii, Marina
Machoshvili, Irene Alexeevna
Marques, Marcelo

Deparment of Biochemical and Pharmaceutical Technology, School of Pharmaceutical Science, University of São Paulo, Rua Antonio de Macedo Soares, 452, São Paulo, Brazil, 04607-000, E-mail: [email protected]

^*Author to whom all correspondence and reprint requests should be addressed.

Applied Biochemistry and Biotechnology 98–100(9):p 525-538, 2002.

Paper strips inoculated with spores of Bacillus stearothermophilus ATCC 7953 were conventionally dried (lot 1) and lyophilized (lot 2); stored in defined environments of 32 and 86% relative humidity at 10, 25 and 33°C for 210 d; and submitted to moist heat treatments at 121°C. A significant decrease in thermal resistance from initial starting levels was found for lyophilized bioindicators stored at 86% relative humidity. The respective average D_121°C values were 1.55 ± 0.05 and 1.37 ± 0.10 min for lyophilized bioindicators stored at 32 and 86% relative humidity; and 1.65 ± 0.15min and 1.57 ± 0.11 min for dried bioindicators stored in the same environments.