On-line control of fed-batch fermentation of dilute-acid hydrolyzates.

Dilute-acid hydrolyzates from lignocellulose are, to a varying degree, inhibitory to yeast. In the present work, dilute-acid hydrolyzates from spruce, birch, and forest residue, as well as synthetic model media, were fermented by Saccharomyces cerevisiae in fed-batch cultures. A control strategy based on on-line measurement of carbon dioxide evolution (CER) was used to control the substrate feed rate in a lab scale bioreactor. The control strategy was based solely on the ratio between the relative increase in CER and the relative increase in feed rate. Severely inhibiting hydrolyzates could be fermented without detoxification and the time required for fermentation of moderately inhibiting hydrolyzates was also reduced. The feed rate approached a limiting value for inhibiting media, with a corresponding pseudo steady-state value for CER. However, a slow decrease of CER with time was found for media containing high amounts of 5-hydroxymethyl furfural (HMF). The success of the control strategy is explained by the conversion of furfural and HMF by the yeast during fed-batch operation. The hydrolyzates contained between 1.4 and 5 g/l of furfural and between 2.4 and 6.5 g/l of HMF. A high conversion of furfural was obtained (between 65-95%) at the end of the feeding phase, but the conversion of HMF was considerably lower (between 12-40%).

[1]  G. J. Hajny,et al.  Fermentation of wood sugars to ethyl alcohol , 1945 .

[2]  G. Villa,et al.  Microbial transformation of furfural to furfuryl alcohol by saccharomyces cerevisiae , 1992 .

[3]  L. Gustafsson,et al.  Characterization and fermentation of dilute-acid hydrolyzates from wood , 1997 .

[4]  Bärbel Hahn-Hägerdal,et al.  Fermentation of lignocellulosic hydrolysates. I: inhibition and detoxification , 2000 .

[5]  J S Almeida,et al.  Influence of furfural on anaerobic glycolytic kinetics of Saccharomyces cerevisiae in batch culture. , 1999, Biotechnology and bioengineering.

[6]  Leif J. Jönsson,et al.  Comparison of different methods for the detoxification of lignocellulose hydrolyzates of spruce , 1999 .

[7]  L. Olsson,et al.  Fermentation of lignocellulosic hydrolysates for ethanol production. , 1996 .

[8]  Mohammad J. Taherzadeh,et al.  Conversion of dilute-acid hydrolyzates of spruce and birch to ethanol by fed-batch fermentation , 1999 .

[9]  Per Hagander,et al.  A probing feeding strategy for Escherichia coli cultures , 1999 .

[10]  Mohammad J. Taherzadeh,et al.  Acetic acid—friend or foe in anaerobic batch conversion of glucose to ethanol by Saccharomyces cerevisiae? , 1997 .

[11]  J. Gaddy,et al.  The effects of furfural on ethanol production by saccharomyces cereyisiae in batch culture , 1992 .

[12]  W. L. Faith.  Development of the Scholler Process in the United States , 1945 .

[13]  J. Villadsen,et al.  Acoustic off-gas analyser for bioreactors: Precision, accuracy and dynamics of detection , 1995 .

[14]  W. A. Scheffers,et al.  Physiology of Saccharomyces cerevisiae in anaerobic glucose-limited chemostat cultures. , 1990, Journal of general microbiology.

[15]  Jerome F. Saeman,et al.  Kinetics of Wood Saccharification - Hydrolysis of Cellulose and Decomposition of Sugars in Dilute Acid at High Temperature , 1945 .

[16]  A. Johnson,et al.  The control of fed-batch fermentation processes - A survey , 1987, Autom..

[17]  Y. Y. Lee,et al.  Ethanol fermentation of crude acid hydrolyzate of cellulose using high‐level yeast inocula , 1985, Biotechnology and bioengineering.

[18]  G Stephanopoulos,et al.  Optimization of fed‐batch penicillin fermentation: A case of singular optimal control with state constraints , 1989, Biotechnology and bioengineering.

[19]  L. Gustafsson,et al.  The effects of pantothenate deficiency and acetate addition on anaerobic batch fermentation of glucose by Saccharomyces cerevisiae , 1996, Applied Microbiology and Biotechnology.

[20]  L. Gustafsson,et al.  Conversion of furfural in aerobic and anaerobic batch fermentation of glucose by Saccharomyces cerevisiae. , 1999, Journal of bioscience and bioengineering.

[21]  Mats Galbe,et al.  Comparison of SO2 and H2SO4 impregnation of softwood prior to steam pretreatment on ethanol production , 1998 .

[22]  G. Lidén,et al.  Physiological response to anaerobicity of glycerol-3-phosphate dehydrogenase mutants of Saccharomyces cerevisiae , 1997, Applied and environmental microbiology.

[23]  J. Bautista,et al.  Effects of furfural and 5-hydroxymethylfurfural on the fermentation of Saccharomyces cerevisiae and biomass production from Candida guilliermondii , 1988 .