Organic Acid Resistance and Toxin Gene Profiles of B. cereus Isolated from Red Pepper Powder

Abstract

AbstractThe objectives of the study were to determine the diversity of organic acid resistance as well as the toxin gene profiles of Bacillus cereus isolated from red pepper powder and to analyze the inhibition kinetics of unstressed type culture and resistant food isolates against organic acids.Among 68 B. cereus isolated from red pepper and processing environmental samples (n = 180), 1.4–16.7% of the cells could survive at 0.5% of acetic, malic and tartaric acid. Parameter α of the Weibull model for type strain were up to threefold lower than for resistant food isolate at 0.2% or lower concentration of organic acid treatment. All the B. cereus isolates were positive for three genes in the nonhemolytic enterotoxin complex (nheA, nheB and nheC), entFM and bceT genes. The ces gene‐encoding emetic toxin was detected in nine (13.2%) of the 68 isolates tested.Practical ApplicationsBacillus cereus is an etiological agent of foodborne illness in Korea. The food products under risk for B. cereus food poisoning are pasteurized (dairy foods or cooked chilled foods) and dry foods. When B. cereus has been exposed to sublethal acid treatment conditions, adapted or resistant strains have developed. Acid resistance of the strain cause a food safety problem because it may result in enhanced protection for cells which are subsequently exposed to lethal heat or hydrogen peroxide stress. The rate of acid resistance and the kinetic parameters of wild type food isolates against organic acid treatment can be used to develop intervention strategies and in risk assessment to assure food safety. A diversity of toxin gene profiles which include diarrheal and emetic toxins also provide useful information in risk assessment of food poisoning caused by B. cereus.