Heike Kahr
Upper Austria University of Applied Sciences Research and Development Ltd, Campus Wels, Austria
Sara Helmberger
Upper Austria University of Applied Sciences Research and Development Ltd, Campus Wels, Austria
Alexander G. Jäger
Upper Austria University of Applied Sciences Research and Development Ltd, Campus Wels, Austria
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http://dx.doi.org/10.3384/ecp11057492Published in: World Renewable Energy Congress - Sweden; 8-13 May; 2011; Linköping; Sweden
Linköping Electronic Conference Proceedings 57:66, p. 492-499
Published: 2011-11-03
ISBN: 978-91-7393-070-3
ISSN: 1650-3686 (print), 1650-3740 (online)
Bioethanol production of lignocellulosics is technologically analyzed; but requires further investigations concerning yield optimization and economic efficiency. One important aspect is to obtain an ideal yeast strain for the fermentation process; which should possess the ability of a stable conversion of C5- and C6-sugars; resistance/tolerance against inhibitory compounds; temperature; ethanol; sugar and industrial stability. The use of genetically-modified microorganisms is reported. Problems with the stability of the microorganisms and public concerns with regard to/about the use of genetically-modified organisms led us to seek other strategies. For this purpose; several yeast strains were adapted to the mentioned characteristics using specific natural adaptation and systematic selection.
For improved utilization of xylose; several yeast strains have been cultivated on xylose-minimal agar for various generations. Yeast strains have been adapted to grow in ascending concentrations of wheat straw hydrolysate medium. Furthermore; several yeast strains have been bred at increased temperatures; with enhanced ethanol and sugar concentrations.
Some xylose- as well as hydrolysate-adapted yeast strains show an increased fermentative competence. A few of the thermally adapted yeast strains represent an enhanced fermentative capacity at higher temperature (42°C). Various yeast strains are tolerant concerning 8-12 % of ethanol and 400-450 g/l of glucose. Some significant improvements concerning ideal yeast strain could have been reached. These improvements offer new possibilities for further optimization.
Lignocellulosic remnant straw; Ideal yeast strain; Natural adaptation; Systematic selection; Bioethanol
