Enzymatic hydrolysis of organosolv-pretreated corncob and succinic acid production by Actinobacillus succinogenes

Abstract

In this study, the conversion of organosolv-treated corncob into monosaccharides through enzymatic saccharification was investigated, with the resulting monosaccharides being utilized as a carbon source to produce succinic acid. The synergy between the cellulase and xylanase provided 76% cellulose and 64% xylan digestibility at 50 °C and pH 5.2. In separate hydrolysis and fermentation (SHF), Actinobacillus succinogenes produced 12.7 g/L of succinic acid from the hydrolysate with 0.12 g/g yield based on the pretreated corncob. Simultaneous saccharification and fermentation (SSF) demonstrated better performance with 16 g/L succinic acid titer and 0.24 g/g yield, though SHF provided a higher production rate. The condition in the SSF (37 °C and pH near neutral) was suboptimal for the enzymes, thus the succinic acid production was limited by the saccharification step. These findings emphasize the potential of organosolv-treated corncob to serve as an enzymatic hydrolysis substrate without neutralization and detoxification, supplying glucose and xylose for succinic acid production by A. succinogenes.