Succinic acid production from sorghum grain: A comparative study of Actinobacillus succinogenes DSM 22257 and Basfia succiniciproducens DSM 22022 strains

Succinic acid (SA) is an important building-block chemical that serves as a precursor for a wide variety of chemicals and materials with significant market value. Its production from renewable sources has attracted considerable attention in recent years. In this work, the suitability of industrial sorghum grain as a feedstock for SA production, using Actinobacillus succinogenes DSM 22257 and Basfia succiniciproducens DSM 22022, was studied. The addition of phosphates and salts (10% v/v), yeast extract (6 g/L), and corn steep liquor (10 g/L) to the industrial sorghum-based medium was necessary for achieving the best results for both strains. A. succinogenes showed better fermentation kinetics and higher SA concentration than B. succiniciproducens in all fermentations, reaching 28.8 g/L at 24 h for A. succinogenes and 21.7 g/L at 48 h for B. succiniciproducens. When the fermentation was scaled-up to a bioreactor, A. succinogenes showed no significant differences when using MgCO3 or CO2 without and with pH control, respectively. These results suggest that the production of SA using A. succinogenes has significant potential for CO2 sequestration, contributing to the reduction of atmospheric CO2.