Pretreatment of spruce and oak by N-methylmorpholine-N-oxide (NMMO) for efficient conversion of their cellulose to ethanol.
Pretreatment of softwood spruce and hardwood oak with an industrial cellulose solvent, N-methylmorpholine-N-oxide (NMMO), was investigated prior to enzymatic hydrolysis and fermentation to ethanol. The pretreatments were carried out at 90, 110 and 130 degrees C for 1-3 h with 85% NMMO solution, followed by non-isothermal simultaneous saccharification and fermentation (NSSF). This NSSF included hydrolysis with cellulase and beta-glucosidase for 24 h at 45 degrees C, followed by continuous saccharification and fermentation with Saccharomyces cerevisiae at 37 degrees C for 3 days. The NSSF of untreated oak and spruce resulted in 18.6% and 6.8% ethanol compared to the maximum theoretical yield. However, the pretreatment of oak and spruce at 130 degrees C resulted in almost total conversion of cellulose to ethanol and improved ethanol yield up to 85.4% and 89%, respectively. These numbers are comparable with ethanol from pure glucose with the same strain, which yielded between 84% and 90% of the theoretical ethanol yield.
Shafiei
Marzieh
M
School of Engineering, University of Borås, Borås, Sweden.
Karimi
Keikhosro
K
Taherzadeh
Mohammad J
MJ
D001709:Biotechnology / Q000379:methods*; D002482:Cellulose / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D005285:Fermentation; D005947:Glucose / Q000737:chemistry; D009025:Morpholines / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013045:Species Specificity; D013696:Temperature; D013997:Time Factors; D014934:Wood
D003497:Cyclic N-Oxides; D009025:Morpholines; D000431:Ethanol; D002482:Cellulose; C067960:4-methylmorpholine N-oxide; D005947:Glucose