Consolidated Bioprocessing of Hemicellulose-Enriched Lignocellulose to Succinic Acid through a Microbial Cocultivation System

Consolidated bioprocessing (CBP) has been considered as a cost-effective strategy for the efficient bioconversion of lignocellulosic biomass into valuable chemicals. Microbial consortium can complete the complex CBP process through the cooperation within different microorganisms. In this study, a proof-of-concept CBP microbial consortium was designed, which is composed of a hemicellulase-producing bacterium Thermoanaerobacterium thermosaccharolyticum M5 and a succinic acid production specialist Actinobacillus succinogenes 130Z. The continuous conversion of xylan to xylose by T. thermosaccharolyticum could maintain a high hydrolyzing rate, which would facilitate the following succinic acid production by A. succinogenes 130Z. After the process optimization including inoculation time, pH, and so forth, 32.50 g/L of succinic acid with a yield of 0.39 g/g was obtained from xylan through CBP, representing the highest succinic acid production directly from hemicellulose materials. In addition, 12.51 g/L of succinic acid was directly produced from 80 g/L of untreated corn cob. These results demonstrated that the proof-of-concept application of this CBP-based microbial cocultivation system could be readily adopted for bioconversion of lignocellulosic biomass into other valuable biochemicals.