Improving Ethanol Production from Lignocellulose Hydrolyzates: Fed-batch Fermentation, Yeast Cultivation and Strain Development for Increased Tolerance
Author
Summary, in English
In aerobic fed-batch cultivation aiming at high biomass yield, it is essential not only to avoid inhibiting concentrations of e.g. furfural and HMF, but also to avoid ethanol formation due to over-flow metabolism. Closed-loop feed-rate control with constant ethanol set-point, allowed a specific biomass productivity of around 0.2 g g-1 h-1 with a yield of 0.46 g biomass/g fermentable sugar. Feeding strategies were also successfully developed for anaerobic fed-batch fermentation. It was possible to increase the specific ethanol productivity several-fold in controlled fed-batches compared to batch fermentation - from 0.06 g g-1 h-1 to 0.7 g g-1 h-1.
In addition to process technology, work was also made concerning inhibitor tolerance of the yeast. An alcohol dehydrogenase enzyme able to reduce HMF was identified using genome-wide analysis. The enzyme ? encoded by the gene ADH6 ? was shown to catalyze NADPH-dependant reduction of HMF and over-expression of the gene gave an increased in vivo HMF conversion ability. Furthermore, the modified yeast showed increased fermentation rate in undetoxified lignocellulose hydrolyzate.
Department/s
Publishing year
2005
Language
English
Document type
Dissertation
Publisher
Chemical Engineering, Lund University
Topic
- Chemical Engineering
Keywords
- Kemiteknik och kemisk teknologi
- Chemical technology and engineering
- Saccharomyces cerevisiae
- fed-batch control
- Ethanol production
- dilute acid hydrolyzate
Status
Published
Supervisor
ISBN/ISSN/Other
- ISBN: 91-628-6461-0
Defence date
21 December 2005
Defence time
10:15
Defence place
Room K:C, Centre for Chemistry and Chemical Engineering, Getingevägen 60, Lund Institute of Technology.
Opponent
- Han de Winde (Professor)