Prediction of Competitive Microbial Growth

Abstract

Prediction of competitive microbial growth is becoming important for microbial food safety. There would be two approaches to predict competitive microbial growth with mathematical models. The first approach is the development of a growth model for competitive microbes. Among several candidates for the competition model considered, the combination of the primary growth model of the new logistic NL model and the competition model of the Lotka-Vorttera LV model showed the best performance in predicting microbial competitive growth in the mixed culture of two species. This system further successfully predicted the growth of three competitive species in mixed culture. The second approach is the application of the secondary model especially for the parameter of the maximum cell population in the primary growth model. The combination of the NL model and a polynomial model for the maximum population successfully predicted Salmonella growth in raw ground beef. This system further successfully predicted Salmonella growth in beef at various initial concentrations and temperatures. The first approach requires microbial growth data in monoculture for analysis. The second approach to the prediction of competitive growth from the viewpoint of microbial food safety would be more suitable for practical application.

Start-Up Performance and Process Kinetics of a Two-Stage Partial Nitrification–Anaerobic Ammonium Oxidation Reactor

“…The start-up process of a microbial reactor involves the growth, reproduction, and expansion of the functional microorganisms, with microorganisms adapting to their environment during start-up and propagation and expansion occurring during loading. Correspondingly, an improvement in the treatment effect of the microbial reactor can mark an increase in the microbial population [29]. However, the growth of microorganisms is not unlimited and is affected by the living space, nutrient concentration, and other conditions.…”

Peeling back the many layers of competitive exclusion

“…One of the earliest examples of fecal transplants was done in chickens, where cecal bacteria from mature hens were shown to block Salmonella colonization in chicks ( Nurmi and Rantala, 1973 ). This phenomenon was later termed competitive exclusion, even though it was not known whether competition ( Fujikawa, 2016 ) was at the heart of the exclusion mechanism. Fecal transplants with the intestinal microbiota from adult chickens have also been shown to dramatically reduce Salmonella prevalence in broiler chickens in the field ( Wierup et al, 1988 ; Hirn et al, 1992 ).…”