title: Fermentation of lignocellulosic hydrolysate by the alternative industrial ethanol yeast Dekkera bruxellensis.
abstract: OBJECTIVE
  Testing the ability of the alternative ethanol production yeast Dekkera bruxellensis to produce ethanol from lignocellulose hydrolysate and comparing it to Saccharomyces cerevisiae.
  
  
  RESULTS
  Industrial isolates of D. bruxellensis and S. cerevisiae were cultivated in small-scale batch fermentations of enzymatically hydrolysed steam exploded aspen sawdust. Different dilutions of hydrolysate were tested. None of the yeasts grew in undiluted or 1:2 diluted hydrolysate [final glucose concentration always adjusted to 40 g l⁻¹ (0.22 mol l⁻¹)]. This was most likely due to the presence of inhibitors such as acetate or furfural. In 1:5 hydrolysate, S. cerevisiae grew, but not D. bruxellensis, and in 1:10 hydrolysate, both yeasts grew. An external vitamin source (e.g. yeast extract) was essential for growth of D. bruxellensis in this lignocellulosic hydrolysate and strongly stimulated S. cerevisiae growth and ethanol production. Ethanol yields of 0.42 ± 0.01 g ethanol (g glucose)⁻¹ were observed for both yeasts in 1:10 hydrolysate. In small-scale continuous cultures with cell recirculation, with a gradual increase in the hydrolysate concentration, D. bruxellensis was able to grow in 1:5 hydrolysate. In bioreactor experiments with cell recirculation, hydrolysate contents were increased up to 1:2 hydrolysate, without significant losses in ethanol yields for both yeasts and only slight differences in viable cell counts, indicating an ability of both yeasts to adapt to toxic compounds in the hydrolysate.
  
  
  CONCLUSIONS
  Dekkera bruxellensis and S. cerevisiae have a similar potential to ferment lignocellulose hydrolysate to ethanol and to adapt to fermentation inhibitors in the hydrolysate.
  
  
  CONCLUSIONS
  This is the first study investigating the potential of D. bruxellensis to ferment lignocellulosic hydrolysate. Its high competitiveness in industrial fermentations makes D. bruxellensis an interesting alternative for ethanol production from those substrates.
authors.affiliation: Department of Microbiology, Uppsala Biocenter, Swedish University of Agricultural Sciences, Uppsala, Sweden. johanna.blomqvist@slu.se
authors.forename: J
authors.initials: J
authors.lastname: Blomqvist
authors.forename: E
authors.initials: E
authors.lastname: South
authors.forename: I
authors.initials: I
authors.lastname: Tiukova
authors.forename: L
authors.initials: L
authors.lastname: Tiukova
authors.forename: M H
authors.initials: MH
authors.lastname: Momeni
authors.forename: H
authors.initials: H
authors.lastname: Hansson
authors.forename: J
authors.initials: J
authors.lastname: Ståhlberg
authors.forename: S J
authors.initials: SJ
authors.lastname: Horn
authors.forename: J
authors.initials: J
authors.lastname: Schnürer
authors.forename: V
authors.initials: V
authors.lastname: Passoth
mesh_terms: D056804:Biofuels; D019149:Bioreactors; D055167:Dekkera / Q000378:metabolism*; D000431:Ethanol; D005285:Fermentation; D006868:Hydrolysis; D007218:Industrial Microbiology; D008031:Lignin / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*
chemical_list: D056804:Biofuels; C036909:lignocellulose; D000431:Ethanol; D008031:Lignin