Theoretical calculation of butanol acetone mass ratio by graph theory and its experimental verification in cassava and corn media based butanol fermentations.

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.