Promotion of the Clostridium acetobutylicum ATCC 824 growth and acetone-butanol-ethanol fermentation by flavonoids.

An unexpected promotion effect of Ginkgo leaf on the growth of Clostridium acetobutylicum ATCC 824 and acetone-butanol-ethanol (ABE) fermentation was investigated. Component analysis of Ginkgo leaf was carried out and flavonoids were determined as the potential key metabolites. Then the flavonoids feeding experiments were carried out. Results showed that addition of only 10 mg/L flavonoids to the fermentation broth can promote butanol and ABE titre up to 14.5 and 17.8 g/L after 5 days of fermentation, that is, 74 and 68% higher than the control. A 2.2-fold biomass also has been achieved. Furthermore, by employing such novel founding, we easily exploited flavonoids from soybean and some agriculture wastes as the wide-distributed and economic feasible ABE fermentation promoter. The mechanism of the above effects was investigated from the perspective of oxidation-reduction potential. This work opens a new way in the efforts to increase the titer of butanol.