Abstract:Glucose-based media containing different contents of yeast extract were used to culture Clostridium acetobutylicum, either in the acidogenic or in the solventogenic phase. The fermentation performances in the different period were concerned, including gas production, glucose consumption, organic acids and solvents production, and phase-shift, in order to explore the effects of carbon/nitrogen(C/N) ratio on butanol fermentation performances. The results indicated that a moderate C/N ratio(46.7~93.4 mol/mol) in the acidogenesis could maintain the normal growth rate of strain without large accumulation of organic acids, which resulted in a smooth switch of phase-shift and shortening fermentation time. While a higher C/N ratio(93.4~186.7 mol/mol) in the solventogenesis was benefit for restraining the synthesis of by-product solvents acetone and ethanol, and simultaneously kept the butanol production upon 12 g/L, leading to a relatively high ratio of butanol to total solvent. Moreover, three kinds of biomasses which contained distinct C/N ratios were used as substrate for butanol fermentation. The results further demonstrate the conclusion acquired above about the impacts on fermentation performances brought by C/N ratio alteration of substrate.
