Abstract
Efficient xylose catabolism in engineered Saccharomyces cerevisiae enables more economical lignocellulosic biorefinery with improved production yields per unit of biomass. Yet, the product profile of glucose/xylose co-fermenting S. cerevisiae is mainly limited to bioethanol and a few other chemicals. Here, we introduced an n-butanol-biosynthesis pathway into a glucose/xylose co-fermenting S. cerevisiae strain (XUSEA) to evaluate its potential on the production of acetyl-CoA derived products. Higher n-butanol production of glucose/xylose co-fermenting strain was explained by the transcriptomic landscape, which revealed strongly increased acetyl-CoA and NADPH pools when compared to a glucose fermenting wild-type strain. The acetate supplementation expected to support acetyl-CoA pool further increased n-butanol production, which was also validated during the fermentation of lignocellulosic hydrolysates containing acetate. Our findings imply the feasibility of lignocellulosic biorefinery for producing fuels and chemicals derived from a key intermediate of acetyl-CoA through glucose/xylose co-fermentation.
Highlights
Lignocellulosic biomass offers a sustainable and environmentally friendly source of raw materials for producing fuels and chemicals (Ko and Lee 2018)
To develop an S. cerevisiae strain capable of n-butanolproduction, genes that were previously reported to support butanol biosynthesis were introduced in an efficient glucose/ xylose co-fermenting strain, XUSEA (Hoang Nguyen Tran et al, 2020), with various combinations
Encouraged by the increased n-butanol production during glucose/xylose co-fermentation in the presence of acetate, we evaluated the n-butanol-production performance of XUSAEA-B from lignocellulosic hydrolysates of Miscanthus sacchariflorus Goedae-Uksae, which were prepared through a H2SO4-catalyzed hydrothermal process (Figure 6)
Summary
Lignocellulosic biomass offers a sustainable and environmentally friendly source of raw materials for producing fuels and chemicals (Ko and Lee 2018). Commercial bioethanol production has been achieved using the yeast Saccharomyces cerevisiae and sugar- or starch-based biomass. To improve the economic feasibility of lignocellulosic biorefinery, S. cerevisiae strains have been engineered to coferment glucose and xylose, the most abundant hexose and pentose sugars in lignocellulosic hydrolysates, respectively, resulting in significantly improved lignocellulosic bioethanol yields, titers, and productivity (Hoang Nguyen Tran et al, 2020). Increasing efforts have been devoted to expanding the product profile of S. cerevisiae to include advanced fuels and chemicals demonstrating the great potential of microbial cell factories for biorefinery (Ekas et al, 2019). It is necessary to evaluate the feasibility of sustainable-biorefinery concepts based on lignocellulosic biomass, which is the most abundant and sustainable resource
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