Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2018
Publication Date: 2/14/2018
Citation: Huang, L. 2018. Growth of non-toxigenic clostridium botulinum mutant LNT01 in cooked beef: one-step kinetic analysis and comparison with C. sporogenes and C. perfringens. Food Research International. 107:248-256.
Interpretive Summary: Clostridium botulinum is a serious foodborne pathogen and may be present in various foods. Understanding its growth kinetics is necessary for assessing the safety of meat products. Due to safety concerns, it is difficult to use and test Clostridium botulinum directly in foods in laboratories. This study uses Clostridium botulinum LNT01, a non-toxigenic mutant of C. botulinum 62A, to study its growth kinetics and develop predictive models in cooked ground beef. The mathematical models developed from this study may be used by regulatory agencies for assessing the safety of meat products and prevent foodborne botulism.
Technical Abstract: The objective of this study was to investigate the growth kinetics of Clostridium botulinum LNT01, a non-toxigenic mutant of C. botulinum 62A, in cooked ground beef. The spores of C. botulinum LNT01 were inoculated to ground beef and incubated anaerobically under different temperature conditions to observe growth and develop growth curves. A one-step kinetic analysis method was used to analyze the growth curves to minimize the global residual error. The data analysis was performed used the USDA IPMP-Global Fit, with the Huang model as the primary model and the cardinal parameters model as the secondary model. The results of data analysis showed that the minimum, optimum, and maximum growth temperatures of this mutant are 11.5, 36.4, and 44.3 degrees C, and the estimated optimum specific growth rate is 0.633 ln CFU/g per h, or 0.275 log CFU/g per h. The maximum cell density is 7.84 log CFU/g. Both isothermal and dynamic growth curves were used to validate the growth models and kinetic parameters. The residual errors of validation followed a Laplace distribution, with about 60% of the residual errors within ±0.5 log CFU/g of observations, suggesting that these models could predict the growth of C. botulinum LNT01 in ground beef with a reasonable accuracy. Comparing with C. perfringens, C. botulinum LNT01 would grow much slower rates and with much longer lag times. Its growth kinetics is very similar to C. sporogenes in ground beef. The results of computer simulation using kinetic models show that, while prolific growth of C. perfringens may occur in ground beef during cooling, no growth of C. botulinum LNT01 would occur under the same conditions.