title: Phenotypic characterisation of Saccharomyces spp. yeast for tolerance to stresses encountered during fermentation of lignocellulosic residues to produce bioethanol.
abstract: BACKGROUND
  During industrial fermentation of lignocellulose residues to produce bioethanol, microorganisms are exposed to a number of factors that influence productivity. These include inhibitory compounds produced by the pre-treatment processes required to release constituent carbohydrates from biomass feed-stocks and during fermentation, exposure of the organisms to stressful conditions. In addition, for lignocellulosic bioethanol production, conversion of both pentose and hexose sugars is a pre-requisite for fermentative organisms for efficient and complete conversion. All these factors are important to maximise industrial efficiency, productivity and profit margins in order to make second-generation bioethanol an economically viable alternative to fossil fuels for future transport needs.
  
  
  RESULTS
  The aim of the current study was to assess Saccharomyces yeasts for their capacity to tolerate osmotic, temperature and ethanol stresses and inhibitors that might typically be released during steam explosion of wheat straw. Phenotypic microarray analysis was used to measure tolerance as a function of growth and metabolic activity. Saccharomyces strains analysed in this study displayed natural variation to each stress condition common in bioethanol fermentations. In addition, many strains displayed tolerance to more than one stress, such as inhibitor tolerance combined with fermentation stresses.
  
  
  CONCLUSIONS
  Our results suggest that this study could identify a potential candidate strain or strains for efficient second generation bioethanol production. Knowledge of the Saccharomyces spp. strains grown in these conditions will aid the development of breeding programmes in order to generate more efficient strains for industrial fermentations.
authors.forename: Tithira T
authors.initials: TT
authors.lastname: Wimalasena
authors.forename: Darren
authors.initials: D
authors.lastname: Greetham
authors.forename: Marcus E
authors.initials: ME
authors.lastname: Marvin
authors.forename: Gianni
authors.initials: G
authors.lastname: Liti
authors.forename: Yogeshwar
authors.initials: Y
authors.lastname: Chandelia
authors.forename: Andrew
authors.initials: A
authors.lastname: Hart
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Louis
authors.forename: Trevor G
authors.initials: TG
authors.lastname: Phister
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Tucker
authors.affiliation: Bioenergy & Brewing Science, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, Leicestershire LE12 6RD, UK. katherine.smart@sabmiller.com.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Smart
mesh_terms: D018533:Biomass; D019149:Bioreactors; D016000:Cluster Analysis; D000431:Ethanol / Q000378:metabolism*; D007218:Industrial Microbiology; D008031:Lignin / Q000378:metabolism*; D009994:Osmolar Concentration; D010641:Phenotype; D012440:Saccharomyces / Q000254:growth & development / Q000378:metabolism*; D013312:Stress, Physiological; D013696:Temperature
chemical_list: C036909:lignocellulose; D000431:Ethanol; D008031:Lignin