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Poster Presentation 2-26
The Effect of the Media on Spore Yield and Thermal Resistance of Bacillus stearothermophilus Thereza Christina Vessoni Penna, Marina Ishii, Irene A. Machoshvili Department of Biochemical and Pharmaceutical Technology, School of Pharmaceutical ScienceUniversity of São Paulo, Rua Antonio de Macedo Soares, 45204607-000, São Paulo/SP, Brasil
Telephone: 0055-11-38183694; Fax: 0055-11-38156386; E-mail: tcvpenna@usp.br
The interference of eight components in the yield of sporulation and on thermal resistance of moist heat (121oC) of spores of Bacillus stearothermophilus ATCC 7953, in suspension of calcium acetate solution 0.02M and inoculated on strips previously treated with calcium acetate/ calcium hydroxide (pH 11), was studied. The spore yield of 1.0 x 108 mL-1 was developed at 62oC saturated humidity in 17 media containing different concentrations (w/v) of D-glucose (0.018-0.25%), sodium chloride (0.001-1.0%), L-glutamic acid (0.04%), yeast extract (0.05-0.4%), peptone (0.3-0.5%), manganese sulphate (0.001%), potassium phosphate (0.05%), and ammonium phosphate (0.05%). The thermal resistance was expressed in decimal reduction time (D-value) at 121oC. For media 1 to 6, when potassium phosphate and ammonium phosphate were not included, the D-values for spores in suspension varied from 1.5 min to 2.7 min, and for spores on strips, from 1.7 to 2.1 min. For media 7 to 9, where L-glutamic acid was not added as a component, the mean D-value varied from 1.7 to 2.5 min, both for spores in suspension and on strips. For media 10 to 17, which were made of D-glucose, yeast extract and peptone in agar, the D-value varied from 1.87 min to 2.84 min. A strong influence of associated effects of yeast extract, peptone and glucose contributed positively to the spore yield and to the stability of thermal resistance of spores, which form the BI in suspension and on strips.
Acknowledgement: CAPES, CNPq, FAPESP
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