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P3-06 The Impact of Intrinsic and Extrinsic Factors on the In Vitro Growth of Bacillus cereus

Wednesday, August 3, 2016
America's Center - St. Louis
Young Kyoung Park, Korea University, Sejong, Korea, The Republic of
Martti Tapani Sinnelä, Korea University, Sejong, Korea, The Republic of
Ah Ran Jeon, Korea University, Sejong, Korea, The Republic of
Kwangcheol Jeong, University of Florida, Gainesville, FL
Jae-Hyung Mah, Korea University, Sejong, Korea, The Republic of
Introduction: Foodborne illness resulting from the consumption of foods contaminated with pathogenic bacteria and/or their toxins has considerably heightened the public concerns about the safety of foods. Meanwhile, Bacillus cereus is becoming one of the most important causes of food poisoning although major foodborne pathogenic bacteria mainly include salmonellae, listeriae and certain strains of Escherichia coli.

Purpose: This study was performed to reduce the risk of B. cereus contamination by adjusting intrinsic and extrinsic factors of foods.

Methods: Three B. cereus strains (KCTC 3624, KCTC 1012 and KCTC 1661) of type cultures and one strain (CH3) isolated from Cheonggukjang were used in this study. The inhibitory effects of different intrinsic and extrinsic factors, such as pH (4.0-7.0), salinity (0.5-3.0 and 11.0-14.0%), temperature (26-45ºC) and additives, on the growth of B. cereus were examined with an automated turbidimetric system and paper disc diffusion method which measure the growth curve of B. cereus and the activity of antimicrobial substances, respectively.

Results: The growth of B. cereus was effectively inhibited at pH 4.0-4.5, and followed by pH 5.0. The growth was also significantly reduced at a higher salinity of >11.0%, but less so at a lower salinity of 0.5-3.0%. When the growth curves of B. cereus at different temperatures were compared, the longest lag time (LT) and lowest specific growth rate (SGR) were observed at 26ºC, which means that the strongest inhibitory effect was shown at this lowest temperature examined. Meanwhile, it was found that the growth was significantly reduced by the addition of 1% acetic acid, 1% lactic acid (among organic acids) or 10% Schisandra chinensis extract (among natural substance extracts).

Significance: The data showing the inhibitory effects of intrinsic and extrinsic factors on B. cereus could be comprehensively applied to foods for reducing the risk of B. cereus contamination.

Back to: Poster Session 3 – Antimicrobials, Laboratory and Detection Methods, Microbial Food Spoilage, Modeling and Risk Assessment, Retail and Food Service Safety and Sanitation
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