Comparing the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways in arabinose and xylose fermenting Saccharomyces cerevisiae strains

Bettiga, Maurizio; Hahn‐Hägerdal, Bärbel; Gorwa-Grauslund, Marie-Françoise

doi:10.1186/1754-6834-1-16

Cited by 68 publications

(45 citation statements)

References 52 publications

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“…In all of these cases, extensive downstream overexpression and/or evolutionary engineering is required to improve cell growth and xylose consumption. Even so, these levels are not yet comparable with those of strains expressing an oxidoreductase pathway (4,16,45). Beyond the assembly of xylose catabolic pathways, xylose isomerase is an important enzyme for the food industry, especially in the production of high-fructose corn syrup.…”

mentioning

confidence: 99%

Directed Evolution of Xylose Isomerase for Improved Xylose Catabolism and Fermentation in the Yeast Saccharomyces cerevisiae

Lee

Jellison

Alper

2012

Appl Environ Microbiol

140

132

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The heterologous expression of a highly functional xylose isomerase pathway in Saccharomyces cerevisiae would have significant advantages for ethanol yield, since the pathway bypasses cofactor requirements found in the traditionally used oxidoreductase pathways. However, nearly all reported xylose isomerase-based pathways in S. cerevisiae suffer from poor ethanol productivity, low xylose consumption rates, and poor cell growth compared with an oxidoreductase pathway and, additionally, often require adaptive strain evolution. Here, we report on the directed evolution of the Piromyces sp. xylose isomerase (encoded by xylA) for use in yeast. After three rounds of mutagenesis and growth-based screening, we isolated a variant containing six mutations (E15D, E114G, E129D, T142S, A177T, and V433I) that exhibited a 77% increase in enzymatic activity. When expressed in a minimally engineered yeast host containing a gre3 knockout and tal1 and XKS1 overexpression, the strain expressing this mutant enzyme improved its aerobic growth rate by 61-fold and both ethanol production and xylose consumption rates by nearly 8-fold. Moreover, the mutant enzyme enabled ethanol production by these yeasts under oxygen-limited fermentation conditions, unlike the wild-type enzyme. Under microaerobic conditions, the ethanol production rates of the strain expressing the mutant xylose isomerase were considerably higher than previously reported values for yeast harboring a xylose isomerase pathway and were also comparable to those of the strains harboring an oxidoreductase pathway. Consequently, this study shows the potential to evolve a xylose isomerase pathway for more efficient xylose utilization.

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mentioning

confidence: 99%

Directed Evolution of Xylose Isomerase for Improved Xylose Catabolism and Fermentation in the Yeast Saccharomyces cerevisiae

Lee

Jellison

Alper

2012

Appl Environ Microbiol

140

132

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“…1). Alternatively, heterologous expression of the bacterial xylose isomerase (XI) can be used to covert xylose into xylulose (7)(8)(9)(10). This pathway allows circumventing of the cofactor imbalance problem caused by the different cofactor preferences of XR and XDH.…”

mentioning

confidence: 99%

Combinatorial Design of a Highly Efficient Xylose-Utilizing Pathway in Saccharomyces cerevisiae for the Production of Cellulosic Biofuels

Kim

Eriksen

et al. 2013

Appl Environ Microbiol

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Balancing the flux of a heterologous metabolic pathway by tuning the expression and properties of the pathway enzymes is difficult, but it is critical to realizing the full potential of microbial biotechnology. One prominent example is the metabolic engineering of a Saccharomyces cerevisiae strain harboring a heterologous xylose-utilizing pathway for cellulosic-biofuel production, which remains a challenge even after decades of research. Here, we developed a combinatorial pathway-engineering approach to rapidly create a highly efficient xylose-utilizing pathway for ethanol production by exploring various combinations of enzyme homologues with different properties. A library of more than 8,000 xylose utilization pathways was generated using DNA assembler, followed by multitiered screening, which led to the identification of a number of strain-specific combinations of the enzymes for efficient conversion of xylose to ethanol. The balancing of metabolic flux through the xylose utilization pathway was demonstrated by a complete reversal of the major product from xylitol to ethanol with a similar yield and total by-product formation as low as 0.06 g/g xylose without compromising cell growth. The results also suggested that an optimal enzyme combination depends on not only the genotype/phenotype of the host strain, but also the sugar composition of the fermentation medium. This combinatorial approach should be applicable to any heterologous pathway and will be instrumental in the optimization of industrial production of value-added products.

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“…Further information on this genetic engineering approach is available from references 18,21,47,59,120,134 . The yields of ethanol from xylose by GM strains of S. cerevisiae have been reported at 0.43 g/g, with maximum ethanol concentrations achieved at 46.5 g/L 101 .…”

Section: Lignocellulosic Hydrolysate Fermentationsmentioning

confidence: 99%

“…These characteristics especially include abilities of yeast strains to tolerate stresses due to physico-chemical and biological factors during the rigours of industrial fermentation processes (Table XIII). There is a need to develop stress-resistant yeasts for fuel alcohol fermentations, especially strains able to withstand substrate and product toxicity 18 . Some commercially available bioethanol yeast strains can produce ethanol at >10% (v/v) in high solids >20% (w/v) mashes.…”

Section: Bioethanol Fermentations Microbes For Bioethanol Fermentationsmentioning

confidence: 99%

125th Anniversary Review: Fuel Alcohol: Current Production and Future Challenges

Walker

2011

Journal of the Institute of Brewing

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J. Inst. Brew. 117(1), 3-22, 2011Global research and industrial development of liquid transportation biofuels are moving at a rapid pace. This is mainly due to the significant roles played by biofuels in decarbonising our future energy needs, since they act to mitigate the deleterious impacts of greenhouse gas emissions to the atmosphere that are contributors of climate change. Governmental obligations and international directives that mandate the blending of biofuels in petrol and diesel are also acting as great stimuli to this expanding industrial sector. Currently, the predominant liquid biofuel is bioethanol (fuel alcohol) and its worldwide production is dominated by maize-based and sugar cane-based processes in North and South America, respectively. In Europe, fuel alcohol production employs primarily wheat and sugar beet. Potable distilled spirit production and fuel alcohol processes share many similarities in terms of starch bioconversion, fermentation, distillation and co-product utilisation, but there are some key differences. For example, in certain bioethanol fermentations, it is now possible to yield consistently high ethanol concentrations of ~20% (v/v). Emerging fuel alcohol processes exploit lignocellulosic feedstocks and scientific and technological constraints involved in depolymerising these materials and efficiently fermenting the hydrolysate sugars are being overcome. These so-called secondgeneration fuel alcohol processes are much more environmentally and ethically acceptable compared with exploitation of starch and sugar resources, especially when considering utilisation of residual agricultural biomass and biowastes. This review covers both first and second-generation bioethanol processes with a focus on current challenges and future opportunities of lignocellulose-to-ethanol as this technology moves from demonstration pilot-plants to full-scale industrial facilities.

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Comparing the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways in arabinose and xylose fermenting Saccharomyces cerevisiae strains

Cited by 68 publications

References 52 publications

Directed Evolution of Xylose Isomerase for Improved Xylose Catabolism and Fermentation in the Yeast Saccharomyces cerevisiae

Directed Evolution of Xylose Isomerase for Improved Xylose Catabolism and Fermentation in the Yeast Saccharomyces cerevisiae

Combinatorial Design of a Highly Efficient Xylose-Utilizing Pathway in Saccharomyces cerevisiae for the Production of Cellulosic Biofuels

125th Anniversary Review: Fuel Alcohol: Current Production and Future Challenges

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