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P1-108 The Effect of Sporulation Temperature on the Heat Resistance of Clostridium botulinum Type A Spores

Monday, July 29, 2013
Exhibit Hall (Charlotte Convention Center)
Kristin Marshall, U.S. Food and Drug Administration, Bedford Park, IL
Louis Nowaczyk, U.S. Food and Drug Administration, Bedford Park, IL
Guy Skinner, U.S. Food and Drug Administration, Bedford Park, IL
Rukma Reddy, U.S. Food and Drug Administration, Bedford Park, IL
Gregory Fleischman, U.S. Food and Drug Administration, Bedford Park, IL
John Larkin, U.S. Food and Drug Administration, Bedford Park, IL
Introduction: Spores produced by proteolytic strains of Clostridium botulinum are extremely resistant to high temperatures and thus are the primary food safety risk for thermally processed food products. The temperature at which bacterial endospores are formed is believed to significantly impact the thermal resistance.  

Purpose: To determine the effect of sporulation temperature on the heat resistance of C. botulinum type A spores.   

Methods: Spore crops of C. botulinum type A strains 62A and GiorgioA were produced at four different growth temperatures (20, 27, 37 and 41°C) using TPGY broth as the medium. Spore heat resistance was determined by thermal death time (TDT) studies of each spore crop using 105°C (for spores of 62A) and 100°C (for spores of GiorgioA). The D-values were calculated from the negative slope of the survivor curves.

Results: The heat resistance of C. botulinum strain 62A spores was greatest when produced at 27°C and decreased for spores produced above or below 27°C (D105°C values for spores produced at 20°C, 1.64 min; 27°C, 4.00 min; 37°C, 3.68 min, and 41°C, 3.49 min; P < 0.05). Unlike 62A the heat resistance behavior of GiorgioA spores increased with sporulation temperature with spores formed at optimum growth temperatures of 37°C being the most resistant to temperature (D100°Cvalues for spores produced at 20°C, 3.47 min; 27°C, 4.03 min; and 37°C, 5.68 min; P < 0.05). Time to sporulation for GiorgioA was shorter and resulted in higher spore concentrations than for 62A at 20°C, 27°C and 37°C, and no spores of GiorgioA were produced at 41°C.

Significance: Sporulation temperature greatly affects the heat resistance of C. botulinum spores, and varies by strain. Knowledge of the effect of sporulation temperature on the heat resistance of C. botulinum spores is vital for the production of spores utilized in thermal inactivation studies.

Back to: Poster Session 1 - Risk Assessment, Food Toxicology, Beverages & Water, Meat & Poultry, Dairy & Other Food Commodities, Food Defense, Communication Outreach & Education, Non-microbial Food Safety, General Microbiology, Epidemiology, Seafood, Microbial Foo
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