强化利用丙丁梭菌发酵生产丁醇的主要方法有:添加电子载体强化NADH再生速率、通CO气体抑制氢化酶活性、外添少量丁酸等.但是,上述方法存在着总溶剂产量低、精制成本高、辅料价格昂贵等缺点.本研究通过向丙酮-丁醇-乙醇(ABE)发酵液添加少量电子受体(Na2SO4/CaSO4,2g/L),使得梭菌胞内的电子穿梭传递系统的电子流和质子流发生改变,较多电子e–和质子H+走向NADH合成途径,有利于丁醇合成;电子受体添加还可以促进对梭菌生存/丁醇合成的"有益"氨基酸、特别是缬氨酸的胞内积累/分泌,进一步强化了丁醇生产.在7L罐规模的发酵条件下、添加2g/L的电子受体Na2SO4,ABE发酵的丁醇浓度达到12.96g/L的最高水平,丁醇/丙酮比也有提高,分别比对照组提高35%和10%.添加Na2SO4等廉价电子受体提高了ABE发酵中的丁醇浓度,虽然提高幅度有限,但却可为利用发酵工程技术提高丁醇浓度和丁醇/丙酮比提供一种新的途径.%The common techniques/methods for enhancing butanol synthesis in ABE fermentation by Clostridium acetobutylicum include adding electron carrier to increase NADH regeneration rate, repressing hydrogenase via aerating CO,supplementing small amount of butyrate,etc.However,those methods suffer from the problems of total solvent decrease,purification cost-up to remove pigments, high butyrate cost,etc.In this study,small amount of electron receptors(Na2SO4/CaSO4,2g/L)were added into the ABE fermentation broth: leading to the electron/proton flow transition/changes in the intracellular electron shuttle-transportation system,directing more electron/proton into the NADH regeneration route which enhanced for butanol synthesis; promoting the intracellular accumulation or secretion of those amino acids beneficial for cells survival/butanol synthesis,particularly valine. In the ABE fermentation in a 7L fermentor,by adding 2g/L electron receptor(Na2SO4),the butanol concentration reached the highest levels of 12.96g/L and butanol/acetone ratio also enhanced,the increments were 35% and 10%,respectively compared with those of control. The addition of the cheap electron receptor,such as Na2SO4,could increase the butanol concentration though the increment was limited,but it would supply a new and alternative fermentative method for enhancing butanol synthesis and butanol/acetone ratio.
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