2,3-butanediol production by Enterobacter aerogenes:: selection of the optimal conditions and application to food industry residues

Optimum values of temperature, pH, and starting substrate concentration are experimentally determined for 2,3-butanediol production by Enterobacter aerogenes through three set of batch fermentations of synthetic glucose solutions. The results of tests carried out at variable temperature show an optimum of 39 degreesC and are used to estimate, for both fermentation and thermal inactivation, the activation enthalpies (7.19 and 23.6 kJ mol(-1)) and the related entropies (-0.32 and -0.27 kJ mol(-1) K-1). An optimum pH value of 6.0 is evidenced from batch runs at variable pH, whose results are also used to make reasonable hypotheses on the reaction controlling the metabolic pathway which leads to butanediol. The fermentability of different food industry wastes, namely starch hydrolysate, both ra iv and decoloured molasses, and whey, is finally checked.