Print Email Facebook Twitter Towards fermentation of galacturonic acid-containing feedstocks with Saccharomyces cerevisiae Title Towards fermentation of galacturonic acid-containing feedstocks with Saccharomyces cerevisiae Author Huisjes, E.H. Contributor Pronk, J.T. (promotor) Faculty Applied Sciences Department Department of Biotechnology Date 2013-09-06 Abstract The ambition to reduce our current dependence on fossil transportation fuels has driven renewed interest in bioethanol. Pectin-rich feedstocks like sugar beet pulp and citrus peel, which are currently sold as cattle feed, are promising raw materials for the production of bioethanol. This thesis explores the challenges related to the fermentation of pectin-rich hydrolysates with Saccharomyces cerevisiae. Galacturonic acid is a major constituent of pectin-rich hydrolysates. Achieving efficient conversion of this compound is desired. This requires introduction of a heterologous pathway for galacturonate metabolism. In this project, we functionally expressed uronate isomerase and tagaturonate dehydrogenase, the first two enzymes of a bacterial catabolic pathway. Introduction of the entire 5-enzyme catabolic route did not result in a S. cerevisiae strain capable of galacturonic acid fermentation. Galacturonic acid will therefore remain present in the fermentation medium. It was shown that the presence of galacturonic acid negatively affects fermentation characteristics in aerobic chemostat cultivations. In addition, it was demonstrated that, especially at low pH, galacturonic acid has a drastic impact on cellular viability and galactose, arabinose and xylose consumption. As long as galacturonic acid is not consumed by S. cerevisiae, these inhibitory effects of galacturonic acid will remain a key issue in the yeast-based production of bioethanol and other products from pectin-rich feedstocks. Subject Saccharomyces cerevisiaeyeastbiotechnologymetabolic engineeringbioethanolgalacturonic acid To reference this document use: https://doi.org/10.4233/uuid:c3b977ac-dbf1-4c62-8ceb-23212ff0dcc0 Embargo date 2013-09-08 ISBN 9789053357231 Part of collection Institutional Repository Document type doctoral thesis Rights (c) 2013 Huisjes, E.H. Files PDF PhD_thesis_Eline_Huisjes.pdf 2.59 MB Close viewer /islandora/object/uuid:c3b977ac-dbf1-4c62-8ceb-23212ff0dcc0/datastream/OBJ/view