Year: 1987
Type: article
Abstract: Much progress has been made since the discovery that some yeasts can ferment D-xylose to ethanol.' Initially, only a few yeasts were found that could produce ethanol from D-~ylose.*'~Today, at least eight species of yeasts are known to produce significant amounts of ethanol from D -~y l o s e .~, ~-~ Three of these species have been studied extensively: Pachysolen tannophilus, Candida shehatae, and Pichia stipitis.Under oxygen-limited conditions C. sheharue and P. sripitis are capable of faster specific fermentation rates than is P. tannophilus.Specific fermentation rates in aerated culture as high as 0.30 and 0.48 g/g/h have been reported for P. stipitis and C. shehatae, respectively.'A corresponding value of 0.12 g/g/h has been reported for P. tannophilus.On the other hand, the specific fermentation rates of these three organisms in unaerated culture are not that different.Values of 0.06, 0.09, and 0.07 g/g/h have been reported for P. tannophilus, C. shehatae, and P. stipitis, respectively.'We chose to investigate the aerobic mode of ethanol production by C .shehatae because high fermentation rates are obtained with low aeration using this organism.The objectives of this work were to determine the effects of important process variables such as aeration rate, D-xylose concentration and ethanol concentration on the fermentation rate, and to obtain high volumetric ethanol production rates.Continuous methods were used because they allow collection of accurate rate data at constant environmental conditions.Such data facilitate the development of a kinetic model describing the effects of process variables.We were especially interested in fermentation performance at high volumetric production rates.High volumetric rates re-* To whom all correspondence should be addressed.+ Maintained in cooperation with the University of Wisconsin-Madison.The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader.Such use does not constitute an official endorsement or approval by the U.S.
Source: Biotechnology and Bioengineering
Authors: M. A. Alexander, T. W. Chapman, T. W. Jeffries
Institutions: University of Wisconsin–Madison, Forest Products Laboratory
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W1944527636