Evolutionary engineered Candida intermedia exhibits improved xylose utilization and robustness to lignocellulose-derived inhibitors and ethanol
Artikel i vetenskaplig tidskrift, 2019

The development of robust microorganisms that can efficiently ferment both glucose and xylose represents one of the major challenges in achieving a cost-effective lignocellulosic bioethanol production. Candida intermedia is a non-conventional, xylose-utilizing yeast species with a high-capacity xylose transport system. The natural ability of C. intermedia to produce ethanol from xylose makes it attractive as a non-GMO alternative for lignocellulosic biomass conversion in biorefineries. We have evaluated the fermentation capacity and the tolerance to lignocellulose-derived inhibitors and the end product, ethanol, of the C. intermedia strain CBS 141442 isolated from steam-exploded wheat straw hydrolysate. In a mixed sugar fermentation medium, C. intermedia CBS 141442 co-fermented glucose and xylose, although with a preference for glucose over xylose. The strain was clearly more sensitive to inhibitors and ethanol when consuming xylose than glucose. C. intermedia CBS 141442 was also subjected to evolutionary engineering with the aim of increasing its tolerance to inhibitors and ethanol, and thus improving its fermentation capacity under harsh conditions. The resulting evolved population was able to ferment a 50% (v/v) steam-exploded wheat straw hydrolysate (which was completely inhibitory to the parental strain), improving the sugar consumption and the final ethanol concentration. The evolved population also exhibited a better tolerance to ethanol when growing in a xylose medium supplemented with 35.5 g/L ethanol. These results highlight the potential of C. intermedia CBS 141442 to become a robust yeast for the conversion of lignocellulose to ethanol.

Xylose fermentation

Lignocellulosic bioethanol

Microbial robustness

Non-conventional yeast


David Moreno

Chalmers, Biologi och bioteknik, Industriell bioteknik

Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (Ciemat)

Antonella Carbone

Chalmers, Biologi och bioteknik, Industriell bioteknik

Rosita Pavone

Chalmers, Biologi och bioteknik, Industriell bioteknik

Lisbeth Olsson

Chalmers, Biologi och bioteknik, Industriell bioteknik

Cecilia Geijer

Chalmers, Biologi och bioteknik, Industriell bioteknik

Applied Microbiology and Biotechnology

0175-7598 (ISSN) 1432-0614 (eISSN)

Vol. 103 3 1405-1416

Attraktiv icke-GMO-jäst för bioetanolindustrin

Energimyndigheten (38779-1), 2014-07-01 -- 2015-09-30.

Mot robust och effektiv xylosjäsning av lignocellulosa till etanol

Energimyndigheten (2015-007020), 2016-01-01 -- 2017-12-31.


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