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Novel Propagation Strategy of Saccharomyces cerevisiae for Enhanced Xylose Metabolism during Fermentation on Softwood Hydrolysate

1
Terranol A/S, A.C. Meyers Vænge 15, 2450 Copenhagen, Denmark
2
Section for Sustainable Biotechnology, Aalborg University Copenhagen, 2450 Copenhagen, Denmark
*
Author to whom correspondence should be addressed.
Academic Editor: Nhuan Nghiem
Fermentation 2021, 7(4), 288; https://doi.org/10.3390/fermentation7040288
Received: 5 November 2021 / Revised: 26 November 2021 / Accepted: 28 November 2021 / Published: 29 November 2021
(This article belongs to the Section Industrial Fermentation)
An economically viable production of second-generation bioethanol by recombinant xylose-fermenting Saccharomyces cerevisiae requires higher xylose fermentation rates and improved glucose–xylose co-consumption. Moreover, xylose-fermenting S. cerevisiae recognises xylose as a non-fermentable rather than a fermentable carbon source, which might partly explain why xylose is not fermented into ethanol as efficiently as glucose. This study proposes propagating S. cerevisiae on non-fermentable carbon sources to enhance xylose metabolism during fermentation. When compared to yeast grown on sucrose, cells propagated on a mix of ethanol and glycerol in shake flasks showed up to 50% higher xylose utilisation rate (in a defined xylose medium) and a double maximum fermentation rate, together with an improved C5/C6 co-consumption (on an industrial softwood hydrolysate). Based on these results, an automated propagation protocol was developed, using a fed-batch approach and the respiratory quotient to guide the ethanol and glycerol-containing feed. This successfully produced 71.29 ± 0.91 g/L yeast with an average productivity of 1.03 ± 0.05 g/L/h. These empirical findings provide the basis for the design of a simple, yet effective yeast production strategy to be used in the second-generation bioethanol industry for increased fermentation efficiency. View Full-Text
Keywords: second-generation bioethanol; softwood hydrolysate; Saccharomyces cerevisiae; automated propagation strategy; non-fermentable carbon sources; C5/C6 co-consumption; xylose second-generation bioethanol; softwood hydrolysate; Saccharomyces cerevisiae; automated propagation strategy; non-fermentable carbon sources; C5/C6 co-consumption; xylose
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MDPI and ACS Style

Dobrescu, A.C.; Veras, H.C.T.; Varrone, C.; Knudsen, J.D. Novel Propagation Strategy of Saccharomyces cerevisiae for Enhanced Xylose Metabolism during Fermentation on Softwood Hydrolysate. Fermentation 2021, 7, 288. https://doi.org/10.3390/fermentation7040288

AMA Style

Dobrescu AC, Veras HCT, Varrone C, Knudsen JD. Novel Propagation Strategy of Saccharomyces cerevisiae for Enhanced Xylose Metabolism during Fermentation on Softwood Hydrolysate. Fermentation. 2021; 7(4):288. https://doi.org/10.3390/fermentation7040288

Chicago/Turabian Style

Dobrescu, Andreea C., Henrique C.T. Veras, Cristiano Varrone, and Jan D. Knudsen. 2021. "Novel Propagation Strategy of Saccharomyces cerevisiae for Enhanced Xylose Metabolism during Fermentation on Softwood Hydrolysate" Fermentation 7, no. 4: 288. https://doi.org/10.3390/fermentation7040288

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