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Techniques for the Evolution of Robust Pentose-fermenting Yeast for Bioconversion of Lignocellulose to Ethanol
Published on: October 24, 2016
Ethanol fermentation technologies from sugar and starch feedstocks.
F W Bai1, W A Anderson, M Moo-Young
1Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1. fwbai@dlut.edu.cn
Biotechnology Advances
|October 30, 2007
Summary
Zymomonas mobilis offers higher ethanol yield than Saccharomyces cerevisiae but has limitations. Yeast self-immobilization via flocculation is a more economical and effective ethanol production strategy.
Area of Science:
- Biotechnology
- Biochemical Engineering
- Industrial Microbiology
Background:
- Ethanol fermentation technologies using sugar and starch feedstocks require critical review.
- Key aspects of ethanol production, often overlooked, impact efficiency and scalability.
Purpose of the Study:
- To critically review neglected or misunderstood aspects of ethanol fermentation technologies.
- To compare Zymomonas mobilis and Saccharomyces cerevisiae for ethanol production.
- To evaluate yeast immobilization techniques for industrial ethanol production.
Main Methods:
- Comparative analysis of Zymomonas mobilis and Saccharomyces cerevisiae.
- Review of steady-state and dynamic kinetic models for continuous fermentation.
- Evaluation of yeast immobilization techniques (gel entrapment vs. self-immobilization).
Main Results:
- Zymomonas mobilis exhibits higher ethanol yield and productivity due to its Entner-Doudoroff pathway, but faces substrate specificity and biomass limitations.
- Existing kinetic models for continuous fermentation show discrepancies, hindering process optimization.
- Dynamic behavior under high-gravity conditions is understudied, impacting energy efficiency and final ethanol concentration.
- Gel entrapment for yeast immobilization is undesirable due to restrained growth, cost, contamination risks, and economic unfeasibility.
- Self-immobilization through yeast flocculation overcomes drawbacks of artificial immobilization.
Conclusions:
- While Zymomonas mobilis has advantages, Saccharomyces cerevisiae remains relevant due to broader applicability.
- Further research into dynamic modeling and high-gravity fermentation is crucial for optimizing industrial ethanol production.
- Yeast self-immobilization via flocculation presents a superior alternative to artificial immobilization for cost-effective and efficient ethanol fermentation.
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