Simultaneous utilization of glucose and xylose from biomass facilitate the chain elongation of microbial electrosynthesis

Microbial electrosynthesis (MES) is a promising technology for fixing CO2 and producing chemicals. However, elongating CO2 into high value-added products remains a challenge in MES. In this study, glucose and xylose promote the formation of long carbon chain chemicals in MES. The effects of single sugar (glucose or xylose) and mixed sugar (glucose and xylose) on MES with different inoculation sources were investigated. When sediment as used as inoculum, 3.4g/L butyrate and 0.34g/L caproate were obtained in MES with co-addition of glucose and xylose. The results showed that biosynthesis of secondary metabolites and carbon fixation pathway in this strategy were more active and positively correlated with Clostridium through redundancy analysis and Mantel test. Metagenomic analysis showed that the abundance of genes in the fatty acid biosynthesis (FAB) pathway was higher than that of Wood-Ljungdahl (WL) and reverse beta oxidation (RBO) in this strategy. Furthermore, the generation of long carbon chains for MES was verified using straw hydrolysates (including glucose and xylose) from acid treatment and anodic electrooxidation. This study provides an economic and environmental benefits scheme for producing long carbon chain chemicals from the simultaneous use of CO2 and biomass in MES.