Butanol production from hexoses and pentoses by fermentation of Clostridium acetobutylicum

Abstract 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 KH 2 PO 4 –K 2 HPO 4 concentration was increased up to 5 g/L; the MgSO 4 concentration was increased up to 2 g/L; the MnSO 4 concentration was increased up to 0.1 g/L; the FeSO 4 concentration ranged between 0.002 and 0.01 g/L); the CaCO 3 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.