title: Looking beyond Saccharomyces: the potential of non-conventional yeast species for desirable traits in bioethanol fermentation.
abstract: Saccharomyces cerevisiae has been used for millennia in the production of food and beverages and is by far the most studied yeast species. Currently, it is also the most used microorganism in the production of first-generation bioethanol from sugar or starch crops. Second-generation bioethanol, on the other hand, is produced from lignocellulosic feedstocks that are pretreated and hydrolyzed to obtain monomeric sugars, mainly D-glucose, D-xylose and L-arabinose. Recently, S. cerevisiae recombinant strains capable of fermenting pentose sugars have been generated. However, the pretreatment of the biomass results in hydrolysates with high osmolarity and high concentrations of inhibitors. These compounds negatively influence the fermentation process. Therefore, robust strains with high stress tolerance are required. Up to now, more than 2000 yeast species have been described and some of these could provide a solution to these limitations because of their high tolerance to the most predominant stress conditions present in a second-generation bioethanol reactor. In this review, we will summarize what is known about the non-conventional yeast species showing unusual tolerance to these stresses, namely Zygosaccharomyces rouxii (osmotolerance), Kluyveromyces marxianus and Ogataea (Hansenula) polymorpha (thermotolerance), Dekkera bruxellensis (ethanol tolerance), Pichia kudriavzevii (furan derivatives tolerance) and Z. bailii (acetic acid tolerance).
authors.affiliation: Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium.
authors.forename: Dorota
authors.initials: D
authors.lastname: Radecka
authors.affiliation: Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium Laboratory for Process Microbial Ecology and Bioinspirational Management, Cluster for Bioengineering Technology (CBeT), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, B-2860 Sint-Katelijne-Waver, Flanders, Belgium.
authors.forename: Vaskar
authors.initials: V
authors.lastname: Mukherjee
authors.affiliation: Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium.
authors.forename: Raquel Quintilla
authors.initials: RQ
authors.lastname: Mateo
authors.affiliation: Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium.
authors.forename: Marija
authors.initials: M
authors.lastname: Stojiljkovic
authors.affiliation: Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium.
authors.forename: María R
authors.initials: MR
authors.lastname: Foulquié-Moreno
authors.affiliation: Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Flanders, Belgium johan.thevelein@mmbio.vib-kuleuven.be.
authors.forename: Johan M
authors.initials: JM
authors.lastname: Thevelein
mesh_terms: D000890:Anti-Infective Agents / Q000633:toxicity; D019149:Bioreactors / Q000382:microbiology*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D007218:Industrial Microbiology; D013312:Stress, Physiological; D015003:Yeasts / Q000254:growth & development / Q000378:metabolism*
chemical_list: D000890:Anti-Infective Agents; D000431:Ethanol
keywords: bioethanol; non-Saccharomyces; phenotype; stress tolerance; yeasts