On the importance of taking space into account when modeling microbial competition in structured food products

Most of the models discussed up till now in predictive microbiology do not take into account the variability of microbial growth with respect to space. In structured (solid) foods, microbial growth can strongly depend on the position in the food and the assumption of homogeneity can thus, not be accepted: space must be considered as an additional independent variable. In the current paper, a continuous time — two species competition model (proposed in previous work by the authors) is extended to take space into account. The spatio-temporal behavior of the spatially extended model is observed on a coupled map lattice. The smaller motility of the micro-organisms in solid foods allows spatial segregation which causes pattern formation. Evidence is given for the fact that taking space into account indeed has an influence on the behavior (coexistence/extinction) of the populations, which is very important in the field of predictive microbiology, where microbial safety is of major interest.