Kluyveromyces marxianus, an Attractive Yeast for Ethanolic Fermentation in the Presence of Imidazolium Ionic Liquids
by
Nasir Mehmood 1, Ranim Alayoubi 1,2, Eric Husson 1, Cédric Jacquard 3
, Jochen Büchs 4, Catherine Sarazin 1 and Isabelle Gosselin 1,*
Nasir Mehmood 1, Ranim Alayoubi 1,2, Eric Husson 1, Cédric Jacquard 3, Jochen Büchs 4, Catherine Sarazin 1 and Isabelle Gosselin 1,*
1
Unité Génie Enzymatique et Cellulaire UMR-CNRS 7025, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens CEDEX, France
2
Biotechnologies Appliquées LBA3B, Centre AZM, EDST, Université Libanaise, 1300 Tripoli, Lebanon
3
Unité de Recherche Vignes et Vins de Champagne UPRES-EA 4707, Université de Reims Champagne-Ardenne, BP1039, 51687 Reims CEDEX 2, France
4
AVT—Biochemical Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074 Aachen, Germany
*
Author to whom correspondence should be addressed.
Int. J. Mol. Sci. 2018, 19(3), 887; https://doi.org/10.3390/ijms19030887
Received: 30 January 2018 / Revised: 11 March 2018 / Accepted: 14 March 2018 / Published: 16 March 2018
(This article belongs to the Special Issue Ionic Liquids 2018 and Selected Papers from ILMAT IV)
Imidazolium ionic liquids (ILs) are promising solvents for lignocellulosic biomass (LCB) pretreatment and allow the achievement of higher ethanolic yields after enzymatic hydrolysis and ethanolic fermentation. However, residual ILs entrapped in pretreated biomass are often toxic for fermentative microorganisms, but interaction mechanisms between ILs and cells are still unknown. Here we studied the effects of 1-ethyl-3-methylimidazolium acetate [Emim][OAc] and 1-ethyl-3-methylimidazolium methylphosphonate [Emim][MeO(H)PO2] on Kluyveromyces marxianus, a thermotolerant ethanologenic yeast. Morphological impacts induced by ILs on K. marxianus were characterized by Scanning Electron Microscopy analysis and showed wrinkled, softened, and holed shapes. In Yeast-Malt-Dextrose (YMD) medium, K. marxianus tolerated IL additions up to 2% for [Emim][OAc] and 6% for [Emim][MeO(H)PO2]. Below these thresholds, some IL concentrations enhanced ethanolic yields up to +34% by switching the metabolic status from respiratory to fermentative. Finally, K. marxianus fermentation was applied on several substrates pretreated with [Emim][OAc] or [Emim][MeO(H)PO2] and enzymatically hydrolyzed: a model long fiber cellulose and two industrial LCBs, softwood (spruce) and hardwood (oak) sawdusts. The maximum ethanolic yields obtained were 1.8 to 3.9 times higher when substrates were pretreated with imidazolium ILs. Therefore K. marxianus is an interesting fermentative yeast in a second-generation bioethanol process implying IL pretreatment.
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Keywords:
Kluyveromyces marxianus; lignocellulosic biomass; ionic liquids; second-generation bioethanol; respirofermentative metabolism; scanning electron microscopy
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
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MDPI and ACS Style
Mehmood, N.; Alayoubi, R.; Husson, E.; Jacquard, C.; Büchs, J.; Sarazin, C.; Gosselin, I. Kluyveromyces marxianus, an Attractive Yeast for Ethanolic Fermentation in the Presence of Imidazolium Ionic Liquids. Int. J. Mol. Sci. 2018, 19, 887.
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