Enzymatic hydrolysis of agricultural residues by Trichoderma cellulases and the fermentation of the liberated sugars to ethanol

Summary

Five different agricultural residues, barley straw, wheat straw, corn stover, corn stalks and alfalfa stalks were pretreated by steam explosion. The pretreated agricultural residues were then hydrolyzed by the addition of 15 IU of Trichoderma E58 cellulase per gram dry weight of residue. This resulted in the hydrolysis of 46% of the barley straw, 42% of the wheat straw, 38% of the corn stover and corn stalks and 31% of the alfalfa stalks, to reducing sugars after 24 hrs incubation. Water washing the steam treated wheat straw increased the percent hydrolysis of cellulose to glucose from 18% to 35%. When the agricultural residues were fermented to ethanol using a combined hydrolysis and fermentation procedure, the efficiency of hydrolysis was further improved by 8% to 19%, depending on the nature of the substrate.