Continuous cultivation of dilute-acid hydrolysates to ethanol by immobilized Saccharomyces cerevisiae.
The continuous cultivation of immobilized Saccharomyces cerevisiae CBS 8066 on dilute-acid hydrolysates of forest residuals was investigated. The yeast cells were immobilized in 2-4% Ca-alginate beads. The 2% beads were not stable. However, the 3 and 4% beads were stable for at least 3 wk when an extra resource of calcium ions was available in the medium. The continuous cultivation of a dilute-acid hydrolysate by the immobilized cells at dilution rates of 0.3, 0.5, and 0.6 h(-1) resulted in 86, 83, and 79% sugar consumption, respectively, and an ethanol yield between 0.45 and 0.48 g/g. The hydrolysate was fermentable at a dilution rate of 0.1 h(-1) in a free-cell system but washed out at a dilution rate of 0.2 h(-1). The continuous cultivation of a more inhibiting hydrolysate was not successful by either free- or immobilized-cell systems even at a low dilution rate of 0.07 h(-1). However, when the hydrolysate was overlimed, it was fermentable by the immobilized cells at a dilution rate of 0.2 h(-1).
Taherzadeh
M J
MJ
Department of Chemical Reaction Engineering, Chalmers University of Technology, Göteborg, Sweden. mohammad@cre.chalmers.se
Millati
R
R
Niklasson
C
C
D000464:Alginates / Q000378:metabolism; D018914:Cells, Immobilized / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006868:Hydrolysis; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014934:Wood
D000464:Alginates; D006603:Hexuronic Acids; D000431:Ethanol; D020723:Glucuronic Acid; D005947:Glucose