Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10233420 | Enzyme and Microbial Technology | 2005 | 10 Pages |
Abstract
In order to improve the process economy it is important to use as high dry matter content as possible in simultaneous saccharification and fermentation (SSF). However, too high dry matter content often gives rise to severe inhibition of the yeast metabolism, due to the increased levels of toxic compounds. The aim of the present work was to increase the fibrous content in SSF of steam pretreated spruce to 10% by adapting the yeast to the inhibitory substrate and by using a fed-batch process. Both batch and fed-batch approaches were evaluated. The fed-batch experiments were started with a batch fermentation containing 6% dry matter. Fibrous slurry from the pretreatment was then added four times during the first 24Â h giving a final dry matter content corresponding to 10%. The yeast used in the fermentation was produced aerobically on the hemicellulose hydrolysate obtained from the pretreatment. SSF batch and fed-batch experiments with a cell mass concentration of 2, 3 and 5Â g/L were carried out. When adapted yeast was used, the available hexoses were completely converted within 72Â h and the final ethanol concentrations reached 40-44Â g/L. No major differences in performance between batch and fed-batch were seen, but the ethanol productivity during the first 24Â h was higher in the fed-batch SSF experiments, particularly during the experiments with a cell mass concentration of 2 and 3Â g/L.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Bioengineering
Authors
Andreas Rudolf, Malek Alkasrawi, Guido Zacchi, Gunnar Lidén,