Reassessment of the role of CaCO in n-butanol production from pretreated lignocellulosic biomass by Clostridium acetobutylicum.

In this study, the role of CaCO in n-butanol production was further investigated using corn straw hydrolysate (CSH) media by Clostridium acetobutylicum CICC 8016. CaCO addition stimulated sugars utilization and butanol production. Further study showed that calcium salts addition to CSH media led to the increase in Ca concentration both intracellularly and extracellularly. Interestingly, without calcium salts addition, intracellular Ca concentration in the synthetic P2 medium was much higher than that in the CSH medium despite the lower extracellular Ca concentrations in the P2 medium. These results indicated that without additional calcium salts, Ca uptake by C. acetobutylicum CICC 8016 in the CSH medium may be inhibited by non-sugar biomass degradation compounds, such as furans, phenolics and organic acids. Comparative proteomics analysis results showed that most enzymes involved in glycolysis, redox balance and amino acids metabolism were up-regulated with CaCO addition. This study provides further insights into the role of CaCO in n-butanol production using real biomass hydrolysate.