Enzymatic hydrolysis and fermentation of corn stover liquor from magnesium oxide pretreatment without detoxification

Abstract

Corn stover liquor from MgO pretreatment was enzymatically hydrolyzed and fermented without detoxification. It was inferred from the results that glucose and xylose oligomers in corn stover liquor were fully hydrolyzed into glucose and xylose within 8 and 24 h, respectively. Fermentation of hydrolyzed corn stover liquor with E. coli KO11 was completed within 72 h with an ethanol yield and concentration of 96.5% and 7.8 g/L, respectively. Water soluble magnesium acetate formed during MgO pretreatment didn’t reduce enzyme and KO11 activities and functioned as a buffer reagent during hydrolysis and fermentation, thus eliminating the need for additional buffer preparation. Extended fermentation time was caused by aromatic compounds derived from lignin and was eliminated by improving the tolerance of KO11 to corn stover liquor from MgO pretreatment. Direct hydrolysis and fermentation of corn stover liquor from MgO pretreatment eliminated detoxification, simplified bioconversion process, and reduced production cost.