Parametric studies of ethanol production form xylose and other sugars by recombinant <i>Escherichia coli</i>

Beall, D. S.; Ohta, Kazuyoshi; Ingram, L. O.

doi:10.1002/bit.260380311

Cited by 190 publications

(101 citation statements)

References 20 publications

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“…Ethanol production was monitored by gas chromatography as previously described (Beall et al, 1991). Cell lysate (1?25 mg protein) was added to a final volume of 1 ml containing 40 mM NADH and carbon substrate in Buffer A and incubated in screw cap tubes (37 uC, 15 h).…”

Section: Methodsmentioning

confidence: 99%

Construction and expression of an ethanol production operon in Gram-positive bacteria

et al. 2005

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Pyruvate decarboxylase (PDC), an enzyme central to homoethanol fermentation, catalyses the non-oxidative decarboxylation of pyruvate to acetaldehyde with release of carbon dioxide. PDC enzymes from diverse organisms have different kinetic properties, thermal stability and codon usage that are likely to offer unique advantages for the development of desirable Gram-positive biocatalysts for use in the ethanol industry. To examine this further, pdc genes from bacteria to yeast were expressed in the Gram-positive host Bacillus megaterium. The PDC activity and protein levels were determined for each strain. In addition, the levels of pdc-specific mRNA transcripts and stability of recombinant proteins were assessed. From this analysis, the pdc gene of Gram-positive Sarcina ventriculi was found to be the most advantageous for engineering high-level synthesis of PDC in a Gram-positive host. This gene was thus selected for transcriptional coupling to the alcohol dehydrogenase gene (adh) of Geobacillus stearothermophilus. The resulting Gram-positive ethanol production operon was expressed at high levels in B. megaterium. Extracts from this recombinant were shown to catalyse the production of ethanol from pyruvate.

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Section: Methodsmentioning

confidence: 99%

Construction and expression of an ethanol production operon in Gram-positive bacteria

et al. 2005

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“…Industrial microbes such as S. cerevisiae and Zymomonas mobilis do not natively metabolize xylose, and a foreign xylose catabolic pathway must be integrated into these hosts for xylose utilization (4,5). Even for bacteria like E. coli that natively contain the xylose catabolic pathway, xylose utilization rates and growth rates on xylose are low (6). More importantly, utilization of xylose is repressed in the presence of glucose due to a global regulatory mechanism called carbon catabolite repression (CCR), a common phenomenon observed in bacteria and fungi, which results in abundant amounts of xylose unused when cells ferment a glucose-xylose mixture (7,8).…”

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confidence: 99%

Experimental evolution reveals an effective avenue to release catabolite repression via mutations in XylR

Sievert

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Panyon

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Microbial production of fuels and chemicals from lignocellulosic biomass provides promising biorenewable alternatives to the conventional petroleum-based products. However, heterogeneous sugar composition of lignocellulosic biomass hinders efficient microbial conversion due to carbon catabolite repression. The most abundant sugar monomers in lignocellulosic biomass materials are glucose and xylose. Although industrial Escherichia coli strains efficiently use glucose, their ability to use xylose is often repressed in the presence of glucose. Here we independently evolved three E. coli strains from the same ancestor to achieve high efficiency for xylose fermentation. Each evolved strain has a point mutation in a transcriptional activator for xylose catabolic operons, either CRP or XylR, and these mutations are demonstrated to enhance xylose fermentation by allelic replacements. Identified XylR variants (R121C and P363S) have a higher affinity to their DNA binding sites, leading to a xylose catabolic activation independent of catabolite repression control. Upon introducing these amino acid substitutions into the E. coli D-lactate producer TG114, 94% of a glucose–xylose mixture (50 g⋅L−1 each) was used in mineral salt media that led to a 50% increase in product titer after 96 h of fermentation. The two amino acid substitutions in XylR enhance xylose utilization and release glucose-induced repression in different E. coli hosts, including wild type, suggesting its potential wide application in industrial E. coli biocatalysts.

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“…However, using 5-10% ethanol in the blend will have little or no impact on fuel economy [93][94][95][96][97][98][99][100][101][102][103][104] . Further increasing the ethanol by ~20% reduces fuel economy ~1-3% (refs 105-114).…”

Section: Challenges Involved In Large-scale Bio-ethanol Productionmentioning

confidence: 99%

Viable Feedstock Options and Technological Challenges for Ethanol Production in India

2016

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Though improvements in processing and technology are important, the fluctuating price of inputs such as molasses, corn, sugar beet, sugarcane, sweet sorghum, starch, etc. and their seasonal availability play an important role in ethanol industry. As a matter of fact, the ethanol industry based on conventional resources has reached its saturation point. Technologies for ethanol production from lignocellulosics are being developed by scientists world over with the objective of exploiting the potential of a resource, which is otherwise considered a waste, to generate energy. The focus has been to produce ethanol in a cost-effective manner, besides aiming to find use of its by-products as food supplements for cattles, etc. Recent developments like adoption of technologies such as dry grind fractionation, which is now commercially viable, would reduce the cost of milling; wet milling being costintensive and dry milling requiring smaller plants.

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Parametric studies of ethanol production form xylose and other sugars by recombinant Escherichia coli

Cited by 190 publications

References 20 publications

Construction and expression of an ethanol production operon in Gram-positive bacteria

Construction and expression of an ethanol production operon in Gram-positive bacteria

Experimental evolution reveals an effective avenue to release catabolite repression via mutations in XylR

Viable Feedstock Options and Technological Challenges for Ethanol Production in India

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