Aouadhi C.,Pasteur Institute of Tunisia IPT |
Aouadhi C.,University of Nantes |
Aouadhi C.,French National Center for Scientific Research |
Aouadhi C.,National Institute of Agronomy Tunis INAT |
And 4 more authors.
Food Microbiology | Year: 2013
Spores of Bacillus sporothermodurans are known to be contaminant of dairy products and to be extremely heat-resistant. The induction of endospore germination before a heat treatment could be an efficient method to inactivate these bacteria and ensure milk stability. In this study, the nutrient-induced germination of B.sporothermodurans LTIS27 spores was studied. Testing the effect of 23 nutrient elements to trigger an important germination rate of B.sporothermodurans spores, only d-glucose, l-alanine, and inosine were considered as strong independent germinants. Both inosine and l-alanine play major roles as co-germinants with several other amino acids. A central composite experimental design with three factors (l-alanine, d-glucose, and temperature) using response surface methodology was used to optimize the nutrient-induced germination. The optimal rate of nutrient-induced germination (100%) of B.sporothermodurans spores was obtained after incubation of spore for 60min at 35°C in presence of 9 and 60mM of d-glucose and l-alanine, respectively. The results in this study can help to predict the effect of environmental factors and nutrients on spore germination, which will be beneficial for screening of B.sporothermodurans in milk after induction their germination. Moreover, the chosen method of optimization of the nutrient-induced germination was efficient in finding the optimum values of three factors. © 2013 Elsevier Ltd.