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Thermodynamic analysis of fermentation and anaerobic growth of baker’s yeast for ethanol production

Paper ID Volume ID Publish Year Pages File Format Full-Text
24230 43506 2010 8 PDF Available
Title
Thermodynamic analysis of fermentation and anaerobic growth of baker’s yeast for ethanol production
Abstract

Thermodynamic concepts have been used in the past to predict microbial growth yield. This may be the key consideration in many industrial biotechnology applications. It is not the case, however, in the context of ethanol fuel production. In this paper, we examine the thermodynamics of fermentation and concomitant growth of baker’s yeast in continuous culture experiments under anaerobic, glucose-limited conditions, with emphasis on the yield and efficiency of bio-ethanol production. We find that anaerobic metabolism of yeast is very efficient; the process retains more than 90% of the maximum work that could be extracted from the growth medium supplied to the chemostat reactor. Yeast cells and other metabolic by-products are also formed, which reduces the glucose-to-ethanol conversion efficiency to less than 75%. Varying the specific ATP consumption rate, which is the fundamental parameter in this paper for modeling the energy demands of cell growth, shows the usual trade-off between ethanol production and biomass yield. The minimum ATP consumption rate required for synthesizing cell materials leads to biomass yield and Gibbs energy dissipation limits that are much more severe than those imposed by mass balance and thermodynamic equilibrium constraints.

Keywords
Ethanol production; Yeast fermentation; Continuous culture; Thermodynamic analysis; Exergy efficiency
First Page Preview
Thermodynamic analysis of fermentation and anaerobic growth of baker’s yeast for ethanol production
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 147, Issue 2, 17 May 2010, Pages 80–87
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering