Inhibitory Effects of Biomass Degradation Products on Ethanol Fermentation and a Strategy to Overcome Them

Abstract

The influence of buffers, as well as inhibitors such as formic acid, furfural, HMF, guaiacol, and vanillin, on ethanol formation was investigated. Compared to phosphoric buffer, the acetic and citric buffers were less inhibitory on ethanol fermentation. The addition of formic acid (2.5 g/L) to the buffer reduced the ethanol yield by 8%. Guaiacol (3 g/L) and vanillin (2.5 g/L) decreased ethanol production by 50% and 20%, respectively. Furfural and HMF delayed the yeast fermentation without reducing the total yield. The fermentation was seriously inhibited by the mixture of furfural (1 g/L), HMF (1 g/L), formic acid (1 g/L), vanillin (1 g/L), and guaiacol (1 g/L). The ethanol yield of the fermentation based on enzymatic hydrolyzate from treated biomass was 82%. The addition of 1 g/L MgSO4 as a shielding protector rehabilitated nearly 100% of the total yield.