High solid simultaneous saccharification and fermentation of wet oxidized corn stover to ethanol

Enikõ Varga, Helene B. Klinke, K. Réczey, Anne Belinda Thomsen

Research output: Contribution to journalArticle

179 Citations (Scopus)

Abstract

In this study ethanol was produced from corn stover pretreated by alkaline and acidic wet oxidation (WO) (195°C, 15 min, 12 bar oxygen) followed by nonisothermal simultaneous saccharification and fermentation (SSF). In the first step of the SSF, small amounts of cellulases were added at 50°C, the optimal temperature of enzymes, in order to obtain better mixing condition due to some liquefaction. In the second step more cellulases were added in combination with dried baker's yeast (Saccharomyces cerevisiae) at 30°C. The phenols (0.4-0.5 g/L) and carboxylic acids (4.6-5.9 g/L) were present in the hemicellulose rich hydrolyzate at subinhibitory levels, thus no detoxification was needed prior to SSF of the whole slurry. Based on the cellulose available in the WO corn stover 83% of the theoretical ethanol yield was obtained under optimized SSF conditions. This was achieved with a substrate concentration of 12% dry matter (DM) acidic WO corn stover at 30 FPU/g DM (43.5 FPU/g cellulose) enzyme loading. Even with 20 and 15 FPU/g DM (corresponding to 29 and 22 FPU/g cellulose) enzyme loading, ethanol yields of 76 and 73%, respectively, were obtained. After 120 h of SSF the highest ethanol concentration of 52 g/L (6 vol.%) was achieved, which exceeds the technical and economical limit of the industrial-scale alcohol distillation. The SSF results showed that the cellulose in pretreated corn stover can be efficiently fermented to ethanol with up to 15% DM concentration. A further increase of substrate concentration reduced the ethanol yield significant as a result of insufficient mass transfer. It was also shown that the fermentation could be followed with an easy monitoring system based on the weight loss of the produced CO2.

Original languageEnglish
Pages (from-to)567-574
Number of pages8
JournalBiotechnology and Bioengineering
Volume88
Issue number5
DOIs
Publication statusPublished - Dec 5 2004

Fingerprint

Saccharification
Fermentation
Zea mays
Ethanol
Cellulose
Cellulases
Enzymes
Oxidation
Yeast
Saccharomyces cerevisiae
Dried Yeast
Detoxification
Distillation
Phenols
Substrates
Liquefaction
Carboxylic Acids
Carboxylic acids
Weight Loss
Alcohols

Keywords

  • Corn stover
  • Ethanol fermentation
  • High solid concentration
  • Simultaneous saccharification and fermentation (SSF)

ASJC Scopus subject areas

  • Biotechnology
  • Microbiology

Cite this

High solid simultaneous saccharification and fermentation of wet oxidized corn stover to ethanol. / Varga, Enikõ; Klinke, Helene B.; Réczey, K.; Thomsen, Anne Belinda.

In: Biotechnology and Bioengineering, Vol. 88, No. 5, 05.12.2004, p. 567-574.

Research output: Contribution to journalArticle

Varga, Enikõ ; Klinke, Helene B. ; Réczey, K. ; Thomsen, Anne Belinda. / High solid simultaneous saccharification and fermentation of wet oxidized corn stover to ethanol. In: Biotechnology and Bioengineering. 2004 ; Vol. 88, No. 5. pp. 567-574.
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