Butanol production from hexoses and pentoses by fermentation of Clostridium acetobutylicum

•Process was characterized using lignocellulose-hydrolysate representative sugars.•Batch fermentations of single sugars and of mixtures of sugars were performed.•The synthetic medium was optimized in the concentration of each nutritional factor.•The synergic effect of the four sugars produced a high butanol concentration.

The present paper reports the characterization of ABE (acetone-butanol-ethanol) production by Clostridium acetobutylicum DSM 792 for sugars representative of hydrolysed lignocellulosic biomass (glucose, mannose, arabinose, xylose). The attention was focused on: the selection of an optimal medium for the simultaneous conversion of the investigated sugars; the assessment of interference-synergistic effects during the fermentation of mixtures of the investigated sugars.The synthetic medium was optimised in terms of nutritional factors: the KH2PO4–K2HPO4 concentration was increased up to 5 g/L; the MgSO4 concentration was increased up to 2 g/L; the MnSO4 concentration was increased up to 0.1 g/L; the FeSO4 concentration ranged between 0.002 and 0.01 g/L); the CaCO3 concentration was increased up to 10 g/L. The optimal concentration of the investigated factors was assessed and it varied from one sugar to another.The batch fermentations of a mixture of the four sugars highlighted their synergistic effects. Once set the initial concentration of the sugars (60 g/L), the butanol and solvent concentration increased up to 14.6 and 20.6 g/L, respectively, when the four sugars were present.