Succinic acid fermentation by simultaneous saccharification and fermentation (SSF) with cassava flour

Abstract:

[Objective] In order to raising yields and reducing production costs, we optimized succinic acid production from Actinobacillus succinogenes GXAS137 by simultaneous saccharification and fermentation (SSF) with cassava flour as carbon source. [Methods] The important parameters were screened by the single factor experiment and Plackeet-Burman design. Then, the optimum values of the parameters were obtained by orthogonal experiment design. [Results] The results showed that corn steep liquor (CSL) was used as a proper nutrient in the succinic acid production from cassava flour. The optimum medium compositions were determined as (g/L): cassava flour 100, CSL 14, glucoamylase dose 2.0 AGU/g substrate and MgCO3 75. The succinic acid yield reached 69.31 g/L at the optimal condition. The conversion rate of cassava to succinic acid reached 90.01% and succinic acid productivity was 1.44 g/(L·h). The succinic acid content increased by 32.42% than that without the optimized condition (56.86 g/L). The simultaneous saccharification fermentation (SSF) and separated hydrolysis and fermentation (SHF) were compared with 1.3 L fermenter. The results showed that the succinic acid of SSF (72.21 g/L) was superior than SHF. [Conclusion] The high-level succinic acid production and low production cost from cassava flour may facilitate industrial scale application in future.

Key words:Actinobacillus succinogenes, Cassava flour, Plackett-Burman design, Orthogonal experiment design, Succinic acid