A platform for Acetyl-CoA synthesis using xylose as feedstock in Saccharomyces cerevisiae

Examensarbete för masterexamen

Please use this identifier to cite or link to this item: https://hdl.handle.net/20.500.12380/222442
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Type: Examensarbete för masterexamen
Master Thesis
Title: A platform for Acetyl-CoA synthesis using xylose as feedstock in Saccharomyces cerevisiae
Authors: Englund Örn, Oliver
Abstract: Global rise in temperature and diminishing oil reserves has stimulated a market of alternative replacements to traditional petroleum based products. An alternative is the use of a bio refinery capable of converting biomass to the normally petroleum based products. The baker yeast Saccharomyces cerevisiae is an attractive cell factory as its existing large-scale infrastructures for bioethanol production. However, it cannot utilize xylose, an otherwise unusable part of the plant biomass, which represents of utmost importance in the bio-refinery development. To also have a strain capable to produce a wide range of products, it could be used as a platform to base a bio refinery upon. Therefore, the aim of this study is to generate platform strains capable of forming acetyl-CoA, an intermediate metabolite in many of the cells metabolic reactions and also for many other industrially relevant bio-chemicals. With this goal in mind, the metabolism of S. cerevisiae was engineered. The genes encoding an isomerase-based xylose assimilation pathway (RTG, XI, XKS), and a phosphoketolase pathway (XPK, PTA), were cloned into the yeast strain CEN.PK113-5D to enable the yeast to take up and convert xylose into acetyl-CoA. The functionality of this synthetic pathway were evaluated for the production of 3-hydroxypropionic acid via introduction of ACC1** and MCR genes into the engineered strains. By characterisation of all the engineered strains on glucose growth we found increase of acetate production in strains with the phosphoketolase pathway expressed, indicating the in vivo activity of this pathway. However, expression of the xylose assimilation pathway through genome integration did not render the strains able to grow on xylose, suggesting the low efficiency of the assembled xylose assimilation pathway. To overcome this adaptive laboratory evolution is recommended.
Keywords: Livsvetenskaper;Biologiska vetenskaper;Bioinformatik och systembiologi;Life Science;Biological Sciences;Bioinformatics and Systems Biology
Issue Date: 2015
Publisher: Chalmers tekniska högskola / Institutionen för biologi och bioteknik
Chalmers University of Technology / Department of Biology and Biological Engineering
URI: https://hdl.handle.net/20.500.12380/222442
Collection:Examensarbeten för masterexamen // Master Theses

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