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Flocculation causes inhibitor tolerance in Saccharomyces cerevisiae for 2nd generation bioethanol production
University of Borås, School of Engineering. (Biotechnology)
University of Borås, School of Engineering. (Biotechnology)ORCID iD: 0000-0003-4887-2433
2014 (English)In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 80, no 22Article in journal (Refereed) Published
Sustainable development
The content falls within the scope of Sustainable Development
Abstract [en]

Yeast has long been considered the microorganism of choice for second generation bioethanol production due to its fermentative capacity and ethanol tolerance. However, tolerance towards inhibitors derived from lignocellulosic materials is still an issue. Flocculating yeast strains often perform relatively well in inhibitory media, but inhibitor tolerance has never been clearly linked to the actual flocculation ability per se. In this study, variants of the flocculation gene FLO1 were transformed into the genome of the otherwise non-flocculating laboratory yeast strain Saccharomyces cerevisiae CEN.PK 113-7D. Three mutants with distinct differences in flocculation properties were isolated and characterised. The degree of flocculation and hydrophobicity of the cells were correlated to the length of the gene variant. The effect of different strength of flocculation on the fermentation performance of the strains was studied in defined medium with and without fermentation inhibitors as well as in media based on dilute acid spruce hydrolysate. Strong flocculation aided against the readily convertible inhibitor furfural, but not against less convertible inhibitors, such as carboxylic acids. During fermentation of dilute acid spruce hydrolysate, the most strongly flocculating mutant with dense cell flocs showed significantly faster sugar consumption. The modified strain with the weakest flocculation showed a hexose consumption profile similar to the non-transformed strain. These findings may explain why flocculation has evolved as a stress response, and can find application in fermentation-based biorefinery processes on lignocellulosic raw materials.

Place, publisher, year, edition, pages
American Society of Microbiology , 2014. Vol. 80, no 22
Keyword [en]
Resource Recovery
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
URN: urn:nbn:se:hb:diva-1928DOI: 10.1128/AEM.01906-14ISI: 000344161700007PubMedID: 25172866Local ID: 2320/14366OAI: oai:DiVA.org:hb-1928DiVA: diva2:870006
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2016-10-07Bibliographically approved

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CiteExportLink to record
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