Optimizing the balance between heterologous acetate- and CO2-reduction pathways in anaerobic cultures of Saccharomyces cerevisiae strains engineered for low-glycerol production.

Autor:	van Aalst ACA; Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands., Geraats EH; Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands., Jansen MLA; DSM Biotechnology Centre, Alexander Fleminglaan 1, 2613 AX Delft, The Netherlands., Mans R; Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands., Pronk JT; Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands.
Jazyk:	angličtina
Zdroj:	FEMS yeast research [FEMS Yeast Res] 2023 Jan 04; Vol. 23.
DOI:	10.1093/femsyr/foad048
Abstrakt:	In anaerobic Saccharomyces cerevisiae cultures, NADH (reduced form of nicotinamide adenine dinucleotide)-cofactor balancing by glycerol formation constrains ethanol yields. Introduction of an acetate-to-ethanol reduction pathway based on heterologous acetylating acetaldehyde dehydrogenase (A-ALD) can replace glycerol formation as 'redox-sink' and improve ethanol yields in acetate-containing media. Acetate concentrations in feedstock for first-generation bioethanol production are, however, insufficient to completely replace glycerol formation. An alternative glycerol-reduction strategy bypasses the oxidative reaction in glycolysis by introducing phosphoribulokinase (PRK) and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). For optimal performance in industrial settings, yeast strains should ideally first fully convert acetate and, subsequently, continue low-glycerol fermentation via the PRK-RuBisCO pathway. However, anaerobic batch cultures of a strain carrying both pathways showed inferior acetate reduction relative to a strain expressing only the A-ALD pathway. Complete A-ALD-mediated acetate reduction by a dual-pathway strain, grown anaerobically on 50 g L-1 glucose and 5 mmol L-1 acetate, was achieved upon reducing PRK abundance by a C-terminal extension of its amino acid sequence. Yields of glycerol and ethanol on glucose were 55% lower and 6% higher, respectively, than those of a nonengineered reference strain. The negative impact of the PRK-RuBisCO pathway on acetate reduction was attributed to sensitivity of the reversible A-ALD reaction to intracellular acetaldehyde concentrations. (© The Author(s) 2023. Published by Oxford University Press on behalf of FEMS.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu