Strategy for succinic acid production by Actinobacillus succinogenes from sugarcane bagasse

Nowadays the majority of succinic acid produced commercially is made by chemical synthesis. However, attention has been focused on microbial succinic acid production as an alternative to chemical synthesis. This work aims at defining a strategy for succinic acid production by Actinobacillus succinogenes from sugarcane bagasse hemicellulose hydrolysate. Additionally, the Simultaneous Saccharification and Fermentation (SSF) has been processed. In a first approach, three sequencial experimental designs were performed for optimizing the succinic acid production. The first experiment consisted of a 2⁴⁻¹ fractional factorial design, and the second entailed a Central Composite Rotational Design so as to achieve optimal conditions. The optimal concentrations of nutrients predicted by the model were: NaHCO₃, 10,0 g/L; MgSO₄, 0,2 g/L; yeast extract, 2,0 g/L; KH₂PO₄. 5,0 g/L; wich these were experimentally validated. In the third experiment, the fermentation was carried out using a two-level fractional factorial design 2^5-1. The variables analyzed and their levels were: concentration of substrate; yeast extract, temperature, pH and agitation. Under the best conversion conditions, as determined by statistical analysis, the production of succinic acid was carried out bachwise in an instrumented bioreactor using sugarcane bagasse hemicellulose hydrolysate, yielding a concentration of 40,3 g/L, with 80,0 g/L of initial  concentration, at temperature 37ºC and orbital agitation at 150rpm.