Characterization of Heterologous and Native Enzyme Activity Profiles in Metabolically Engineered Zymomonas mobilis Strains During Batch Fermentation of Glucose and Xylose Mixtures

Gao, Qiang; Zhang, Min; McMillan, James D.; Kompala, Dhinakar S.

doi:10.1385/abab:98-100:1-9:341

Cited by 28 publications

(8 citation statements)

References 9 publications

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“…Xylose isomerase (XI) activity was assayed in a reaction mixture containing 1 mM triethanolamine (TEA) (pH 7.5), 0.3 mM NADH, 100 mM xylose, 10 mM MgSO 4 , 4 U/mL SDH (Roche Diagnostics, Indianapolis, IN) and 10 µL of crude cell extract (Gao et al, 2002; Schellenberg et al, 1984). Xylulokinase was assayed by a method a described in Akinterinwa and Cirino (2009).…”

Section: Methodsmentioning

confidence: 99%

“…An important breakthrough came when Zhang et al (1995) successfully applied metabolic engineering to expand its substrate range to xylose. In the ensuing decade, however, xylose metabolism continued to be a focal point of research as it was found that the ability of engineered strains to metabolize xylose was considerably lower than that of glucose and improvement was needed (De Graaf et al, 1999; Gao et al, 2002; Jeon et al, 2005; Kim et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

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Surviving colorectal cancer

Schneider

Malin

Kahn

et al. 2007

Cancer

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BACKGROUND.The number of long‐term survivors after a cancer diagnosis is increasing, yet relatively few studies have addressed survivors' reported symptoms beyond the initial year after diagnosis.METHODS.The symptom reports of 474 survivors of colon and rectal cancer from 5 US metropolitan areas were collected during 2002‐2003 as part a larger study of the quality of care for patients with cancer diagnosed in 1998. The relation between the prevalence of reported symptoms and prior treatments received was analyzed, adjusting statistically for other patient characteristics.RESULTS.Sixty‐nine percent of the survivors had colon cancer and 31% had rectal cancer. The most commonly reported symptoms were “fatigue” (23%), “negative feelings about body appearance” (14%), “diarrhea” (13%), and “constipation” (7%). Higher percentages of respondents attributed health effects to cancer or its treatment including “worry about health” (24%), “physical discomfort” (19%), and “activity limitations” (15%). In general, prior treatment was not associated with symptom prevalence. However, radiation therapy recipients and patients that received a diverting ostomy were more likely than others to report some of the symptoms we studied. Attribution of health effects to disease or treatment did not vary by prior treatment except that recipients of radiation therapy were more likely than others to report limitations in their activities (30% vs 10%; P = .003).CONCLUSIONS.Among colorectal cancer survivors the prevalence of symptoms at 4 years was low and relatively comparable to published estimates for the general population, but some survivors continue to attribute health effects to cancer or its treatment. Cancer 2007. © 2007 American Cancer Society.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surviving colorectal cancer

Schneider

Malin

Kahn

et al. 2007

Cancer

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“…A number of different conversion technologies exist (Farrell et al 2006;Rammamorth et al 2000;Huber et al 2006) for the conversion of cellulosic biomass to biofuels. The predominant differentiation between the conversion options is the primary catalysis system (Foust et al 2008). Biochemical conversion routes rely on biocatalysts, such as enzymes and microbial cells, in addition to heat and chemicals to convert biomass first to an intermediate mixed sugar stream and then to ethanol or other fermentation produced biofuel.…”

Section: Introductionmentioning

confidence: 99%

An economic and environmental comparison of a biochemical and a thermochemical lignocellulosic ethanol conversion processes

et al. 2009

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With the world's focus on rapidly deploying second generation biofuels technologies, there exists today a good deal of interest in how yields, economics, and environmental impacts of the various conversion processes of lignocellulosic biomass to transportation fuels compare. Although there is a good deal of information regarding these conversion processes, this information is typically very difficult to use on a comparison basis because different underlying assumptions, such as feedstock costs, plant size, co-product credits or assumed state of technology, have been utilized. In this study, a rigorous comparison of different biomass to transportation fuels conversion processes was performed with standard underlying economic and environmental assumptions so that exact comparisons can be made. This study looked at promising second-generation conversion processes utilizing biochemical and thermochemical gasification technologies on both a current and an achievable state of technology in 2012. The fundamental finding of this study is that although the biochemical and thermochemical processes to ethanol analyzed have their individual strengths and weaknesses, the two processes have very comparable yields, economics, and environmental impacts. Hence, this study concludes that based on this analysis there is not a distinct economic or environmental impact difference between biochemical and thermochemical gasification processes for second generation ethanol production.

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“…The process and metabolic ethanol yields (Yp and Ym g/g) were calculated as the maximum amounts of ethanol formed per gram of initial fermentable sugars and of total sugar consumed, respectively. The ethanol volumetric productivity and sugar consumption rates (g/l h) were calculated as the amounts of ethanol produced and of sugar consumed per liter of medium per hour, respectively (Gao et al 2002). Lane M, protein molecular weight standard; lanes 1-3, the total proteins in transformants CP4-P1-1, CP4-P2-1, and CP4-P3-1 grown on xylose alone, respectively; lane 4, total protein in CP4 grown on glucose; lanes 5-6, total proteins in CP4 and CP4-P2-1 precultured on glucose alone, respectively; and lane 7, total protein from xylose-grown precultured cells of CP4-P2-1.…”

Section: Analytical Methods and Yield Calculationsmentioning

confidence: 99%

“…Foreign XI and XK enzymes are considered potential rate-limiting enzymes during xylose metabolism (Rogers et al 2007;Gao et al 2002); nevertheless, XK overexpression does not enhance xylose metabolism (Jeon et al 2005). TKT and TAL convert the intermediates of the pentose metabolism pathway into glyceraldehyde 3-phosphate and fructose 6-phosphate, key intermediates Electronic supplementary material The online version of this article (doi:10.1007/s10529-012-0897-4) contains supplementary material, which is available to authorized users.…”

Section: Introductionmentioning

confidence: 99%

Comparison of glucose/xylose co-fermentation by recombinant Zymomonas mobilis under different genetic and environmental conditions

Dong

Zou

et al. 2012

Biotechnol Lett

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Three xylose-fermenting recombinant Zymomonas mobilis strains containing different Peno-talB/tktA operon terminators were engineered. Each showed similar levels of foreign protein expression and xylose fermentation performance. Strain CP4-P2-1 was further used to compare the glucose/xylose co-fermentation under various cultivation environments to improve the efficiency of the process. Optimal co-fermentation was achieved at 30-34 °C and pH 5.5 using xylose-grown preculture cells giving 20.5 g ethanol/l, ethanol productivity of 0.43 g/l h and ethanol yield of 0.44 g/g at 48 h. Adverse culture conditions mainly influenced the efficiency of xylose fermentation but not glucose fermentation. The key factors affecting co-fermentation were also explored at the molecular level. This study provides valuable insights into the effective harnessing of biomass resources.

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Characterization of Heterologous and Native Enzyme Activity Profiles in Metabolically Engineered Zymomonas mobilis Strains During Batch Fermentation of Glucose and Xylose Mixtures

Cited by 28 publications

References 9 publications

Surviving colorectal cancer

Surviving colorectal cancer

An economic and environmental comparison of a biochemical and a thermochemical lignocellulosic ethanol conversion processes

Comparison of glucose/xylose co-fermentation by recombinant Zymomonas mobilis under different genetic and environmental conditions

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