Effect of Sporulation Medium Content in Carbohydrates, Lipids, and Proteins on Outgrowth of Bacillus spp Spores Activated with Heat and Ethanol Solution

Aims: evaluate the effect of the nutrient content of the medium on the sporulation percentage and the efficiency of ethanolic activation on the outgrowth of Bacillus spp.

Place and Duration: Department of Microbiology of the University of Yaoundé I between
june 2020 and September 2021.

Methodology: In order to contribute to the understanding of the effect of the environment of spore origin on the ability to sporulate and outgrow in foods, spores of Bacillus cereus and Bacillus subtilis were produced in different media differenciated by the carbohydrates, lipids and proteins composition. Mathematical models predicting sporulation rates and germination yields of heat- and ethanol-activated spores were evaluated as a function of the factors selected. The reliability of these models was assessed by comparing the predicted values with those obtained in real food.

Results: It was found that spores originating from high carbohydrates and proteins media had high sporulating and germination rates. It was found that the origin of the spores, mainly the carbohydrate and protein content, resulted in high sporulation rates and that spores from nutrient-rich media germinated faster than those from nutrient-poor media. Germination efficiency varied from strain to strain depending on the method of activation and the composition of the medium in which the spores were produced. The mathematical models obtained were validated in food matrices with correlation of predicted and observed values higher than 0.85.

Conclusion: The ethanolic activation of spore varies depending on the strain and the nutrient content especially the fat content in sporulating medium. The proteins and carbohydrates have significant content for thermal activation.