title: Assessing the potential of wild yeasts for bioethanol production.
abstract: Bioethanol fermentations expose yeasts to a new, complex and challenging fermentation medium with specific inhibitors and sugar mixtures depending on the type of carbon source. It is, therefore, suggested that the natural diversity of yeasts should be further exploited in order to find yeasts with good ethanol yield in stressed fermentation media. In this study, we screened more than 50 yeast isolates of which we selected five isolates with promising features. The species Candida bombi, Wickerhamomyces anomalus and Torulaspora delbrueckii showed better osmo- and hydroxymethylfurfural tolerance than Saccharomyces cerevisiae. However, S. cerevisiae isolates had the highest ethanol yield in fermentation experiments mimicking high gravity fermentations (25 % glucose) and artificial lignocellulose hydrolysates (with a myriad of inhibitors). Interestingly, among two tested S. cerevisiae strains, a wild strain isolated from an oak tree performed better than Ethanol Red, a S. cerevisiae strain which is currently commonly used in industrial bioethanol fermentations. Additionally, a W. anomalus strain isolated from sugar beet thick juice was found to have a comparable ethanol yield, but needed longer fermentation time. Other non-Saccharomyces yeasts yielded lower ethanol amounts.
authors.affiliation: Laboratory for Process Microbial Ecology and Bioinspirational Management, Department of Microbial and Molecular Systems (M2S), Cluster for Bioengineering Technology (CBeT), KU Leuven, Campus De Nayer, Fortsesteenweg 30A, 2860, Sint-Katelijne-Waver, Belgium, stefan.ruyters@kuleuven.be.
authors.forename: Stefan
authors.initials: S
authors.lastname: Ruyters
authors.forename: Vaskar
authors.initials: V
authors.lastname: Mukherjee
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Verstrepen
authors.forename: Johan M
authors.initials: JM
authors.lastname: Thevelein
authors.forename: Kris A
authors.initials: KA
authors.lastname: Willems
authors.forename: Bart
authors.initials: B
authors.lastname: Lievens
mesh_terms: D056804:Biofuels / Q000382:microbiology*; D002175:Candida / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D008031:Lignin / Q000378:metabolism; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D004718:Saccharomycetales / Q000378:metabolism
chemical_list: D056804:Biofuels; C036909:lignocellulose; D000431:Ethanol; D008031:Lignin