在丁醇发酵产溶剂阶段,乙酸和丁酸的生成途径、消耗途径同时存在,各自形成一个闭环路径.本研究利用图论对丁醇发酵中丁醇丙酮质量比进行了理论计算,并对以木薯和玉米为原料的丁醇发酵进行了模拟计算,结果表明:丁酸闭环路径(L2环)的代谢强度是影响丁醇丙酮质量比的主要因素,并且L2环的代谢强度越弱,丁醇丙酮质量比越高;与玉米原料丁醇发酵相比,木薯原料发酵的m(丁醇)/m(丙酮)提高了16.7％.实验结果证实了以上计算结果:在传统发酵、油醇萃取发酵和生物柴油萃取发酵中,以木薯(适时添加酵母浸粉)为原料的发酵批次与以玉米为原料的发酵批次相比,由于其丁酸闭环路径代谢强度较弱,相应发酵方式下丁醇丙酮质量比分别提高了12.9％、61.4％和6.7％,而且两种原料相应发酵方式的丁醇总产量和生产效率基本持平.另外,高丁醇丙酮质量比的木薯发酵所得改良型生物柴油中丁醇浓度与玉米发酵的相比提高了16％,性能得到进一步提高.%ABE fermentation is characterized with acetate butyrate formation and re-assimilation in multiple closed reaction loops during solventogenesis phase.In this study,we estimated butanol acetone mass ratio using graph theory for bio-butanol production utilizing cassava and corn based media.Theoretical calculations revealed that the metabolic strength of butyrate loop (L2) dominantly influenced butanol acetone mass ratio and lower metabolic strength in butyrate loop led to a higher butanol acetone mass ratio,and the ratio could be increased by 16.7％ when using cassava based medium.Experimental results confirmed the theoretical estimations:weakened metabolic strength in butyrate loop using cassava based medium led to higher butanol acetone mass ratios in traditional fermentation and extractive fermentations with oleyl alcohol and biodiesel as the extractants,and butanol acetone mass ratios increased by 12.9％,61.4％ and 6.7％,respectively,while butanol yields and productivities stayed at comparably high levels as compared with those of the fermentations using corn based medium.The higher butanol acetone mass ratios also greatly increased butanol content in biodiesel for 16％,which would largely improve quality of property improved biodiesel in turn.
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