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Techniques for the Evolution of Robust Pentose-fermenting Yeast for Bioconversion of Lignocellulose to Ethanol
Published on: October 24, 2016
Xylose anaerobic conversion by open-mixed cultures
Margarida F Temudo1, Tania Mato, Robbert Kleerebezem
1Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. m.f.temudo@tudelft.nl
Applied Microbiology and Biotechnology
|November 19, 2008
Summary
Xylose fermentation by mixed microbial cultures yields similar products to glucose but with a lower biomass yield. Microbes readily switch between sugars, indicating efficient co-utilization in bioprocesses.
Area of Science:
- Biotechnology and Industrial Microbiology
- Biochemical Engineering
- Sustainable Chemistry
Background:
- Agricultural wastes are rich in xylose, a sugar suitable for bioconversion.
- Microbial fermentation converts carbohydrates into valuable volatile fatty acids and alcohols.
- These products serve as precursors for bioplastics and other chemical synthesis.
Purpose of the Study:
- To investigate and compare xylose fermentation by mixed microbial cultures against glucose.
- To analyze the product spectrum and biomass yield for both substrates.
- To assess microbial response to substrate changes and simultaneous feeding.
Main Methods:
- Anaerobic fermentation of xylose and glucose using mixed microbial cultures.
- Comparative analysis of product formation (volatile fatty acids, alcohols).
- Determination of biomass yield (Cmol X/Cmol S) under different substrate conditions.
Main Results:
- Xylose and glucose fermentation produced a comparable product spectrum.
- Xylose fermentation resulted in a higher fraction of carbon converted to catabolic products (butyrate, acetate, ethanol).
- Biomass yield was approximately 20% lower for xylose (0.16 Cmol X/Cmol S) compared to glucose (0.21 Cmol X/Cmol S), likely due to higher ATP demand for xylose uptake.
Conclusions:
- Mixed microbial cultures efficiently ferment xylose, producing valuable chemical building blocks.
- Lower biomass yield on xylose necessitates further optimization for industrial applications.
- Microbial populations exhibit metabolic flexibility, enabling rapid adaptation to glucose pulses and simultaneous co-utilization of glucose and xylose.
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