Modeling Butanol Synthesis in Xylose by Clostridium saccharoperbutylacetonicum

Abstract

To examine the effect of xylose concentration on butanol synthesis by Clostridium saccharoperbutylacetonicum, a kinetic model of acetone-butanol-ethanol fermentation in the media with various xylose concentrations (40 g/L to 60 g/L) was developed and implemented in COPASI. Batch fermentation experiments were conducted to feed and validate the model, and the highest butanol production was achieved in 45 g/L xylose medium. Strong correlations (R2 > 0.91) between model simulation and experimental results were obtained. The modeling results suggested that the reaction rates in R6 (from acetate to acetyl-CoA), R8 (from acetyl-CoA to acetoacetyl-CoA), R9 (from acetoacetyl-CoA to butyryl-CoA), R10 (from butyryl-CoA to butanol), R14 (from butyrate to butyryl-CoA), and R20 (xylose consumption) were higher in groups with an initial xylose of 45 g/L, 50 g/L, or 55 g/L than those in groups with 40 g/L or 60 g/L xylose. In contrast, the reaction rates in R13 (from butyryl-CoA to butyrate) and R16 (from biomass to inactive cells) were lower in groups with initial xylose of 45 g/L, 50 g/L, or 55 g/L than those in groups with 40 g/L or 60 g/L xylose, which indicated that when initial xylose concentration changed, those reactions were affected, which resulted in different butanol syntheses.