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URN etd-0831111-164122 Statistics This thesis had been viewed 2796 times. Download 2124 times. Author Chang-en Huang Author's Email Address No Public. Department Bioengineering Year 2010 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 160 Title Study on increasing yeast glucose consumption for fuel ethanol production at high temperature Keyword yeast extract Kluyveromyces marxianus Saccharomyces cerevisiae high temperature ethanol fermentation thermotolerant yeast thermotolerant yeast high temperature ethanol fermentation Saccharomyces cerevisiae Kluyveromyces marxianus yeast extract Abstract Ethanol fermentation at high temperature can reduce cooling cost of the fermenter. Highly flocculating yeast is easy to precipate in the beer, and is possible to recirculate the yeast to achieve high cell density ethanol fermentation.
A thermotolerant yeast, Kluyveromyces marxianus K21, was employed to investigate the medium formulation to improve the thermotolerant ability. The result indicated that, when supplement with magnesium(Mg2+)、calcium(Ca2+) or trehalose , there is no significantly improvement on glucose consumption rate or thermotolerance. But the glucose consumption rate can be improved by increasing concentration of yeast extract at high temperature. Ethanol concentration of 47.31 g/L was achieved for the K. marxianus K21 in the medium containing 10% (w/v) glucose and 2 % (w/v) yeast extract at 45?C. Glucose concentration more than 10 % (w/v) could not be consumed by the K. marxianus K21.
The cell growth and glucose consumption rate of flocculating yeast strains were improved by 2.0% (w/v) YE at 28 ?C. The maximum ethanol concentration of WP002, 1968 and 1335 strains was reached at 46.97, 48.60 and 48.76 g/L, respectively, in the 10 % (g/L) glucose concentration. The theoretical ethanol conversion rate from glucose was 92.2, 95.3, and 90.4%, respectively. Moreover, increase the fermentation temperature to 38 ?C, the growth and glucose consumption rate of WP002, 1968 and 1335 strains were improved by 2.0% (w/v) YE, and the maximum ethanol concentration was at 43.36, 46.50 and 49.01 (g/L), respectively, in the 10 % (g/L) glucose concentration. The theoretical ethanol conversion rate from glucose was 85.1, 85.3, and 96.1%, respectively. The results indicate that yeast 1335 was the most thermotolerant.
Yeast 1335 strain was applied in batch-fermentation using a medium containing 2.0% (w/v) yeast extract and 25.0% (w/v) glucose, and achieved 105 and 98 gL-1 at 28 and 38?C respectively. Glucose was completely consumed at 28?C after, while 54.9 gL-1 glucose remained unfermented in the beer at 38?C.
Advisor Committee Kow-Jen Duan - advisor
none - co-chair
none - co-chair
Files Date of Defense 2011-07-28 Date of Submission 2011-08-31