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  • 1
    ISSN: 1432-072X
    Keywords: Zymomonas ; Glucose catabolism ; Ethanol inhibition ; 31P NMR in vivo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ethanol inhibition of glucose catabolism in Zymomonas mobilis was investigated using 31P NMR spectroscopy in vivo and of perchloric acid extracts from cell suspensions incubated with 0, 5 and 10% (w/v) ethanol. In vivo 31P NMR experiments revealed slower glucose utilization and decreased levels of nucleoside triphosphates in the presence of 10% ethanol as compared to controls. Using 31P NMR spectroscopy of perchloric acid extracts, intracellular accumulation of 3.4 mM 3-phosphoglycerate was found when 10% ethanol was present in the medium. No accumulation of this metabolite occurred in cells incubated with 0 and 5% ethanol. Enzyme assays confirmed that phosphoglycerate-mutase and enolase were inhibited 31 and 40%, respectively, in the presence of 10% ethanol in the test system. Therefore, under the conditions used the decrease in the fermentative activity of Z. mobilis at high ethanol concentrations is due to inhibition of phosphoglycerate-mutase and enolase.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Key wordsZymomonas mobilis ; Metabolic flux ; analysis ; Sugar phosphates ; Glucose ; Fructose ; Xylose ; 13C-NMR ; In vivo 31P-NMR ; Rate-limiting step
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The reasons for the well-known significantly different behaviour of the anaerobic, gram-negative, ethanologenic bacterium Zymomonas mobilis during growth on fructose (i.e. decreased growth and ethanol yields, increased by-product formation) as compared to that on its second natural substrate, glucose, have remained unexplained. A xylose-fermenting recombinant strain of Z. mobilis that was recently constructed in our laboratory also unexpectedly displayed an increased formation of by-products and a strongly reduced growth rate as compared to the parent strain. Therefore, a comprehensive study employing recently developed NMR-based methods for the in vivo analysis of intracellular phosphorylated pool sizes and metabolic fluxes was undertaken to enable a global characterization of the intracellular metabolic state of Z. mobilis during growth on 13C-labelled glucose, fructose and xylose in defined continuous cultures. The 13C-NMR flux analysis indicated that ribose 5-phosphate is synthesized via the nonoxidative pentose phosphate pathway in Z. mobilis, and it identified a metabolic bottleneck in the recombinant xylose-fermenting Z. mobilis strain at the level of heterologous xylulokinase. The 31P-NMR analyses revealed a global alteration of the levels of intracellular phosphorylated metabolites during growth on fructose as compared to that on glucose. The results suggest that this is primarily caused by an elevated concentration of intracellular fructose 6-phosphate.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 97 (1974), S. 163-168 
    ISSN: 1432-072X
    Keywords: Candida boidinii ; Methanol ; Assimilation ; Incorporation of ; Formaldehyde ; Ribose-Phosphate-Cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hexose phosphate synthetase activity was found in cell-free extracts of methanol-grown Candida boidinii. Incubation of this crude extract with 14C-formaldehyde and D-ribose-5-phosphate leads to incorporation of radioactivity into fructose-and glucose phosphates. Cells grown on glucose lack the hexose phosphate synthetase activity. No hydroxypyruvate reductase activity, the key enzyme of the serine pathway was found. These results indicate that during growth of C. boidinii on methanol, cell constituents are made by a sugar phosphate pathway similar in concept, if not in absolute molecular detail, to the ribose phosphate cycle in C1-metabolizing bacteria.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 84 (1972), S. 29-42 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Aus einer Bodenprobe wurde eine Hefe, Candida boidinii, isoliert, welche auf Methanol als einziger C-Quelle wachsen kann. Als Wachstumsfaktor benötigt dieser Hefestamm Biotin in sehr geringer Konzentration. Unter günstigen Kulturbedingungen beträgt die Zellausbeute pro 1000 ml Kulturmedium 2,3g Trockenmasse bei Zugabe von 1% (v/v) Methanol, und 8,3g bei 4% Methanol. Das Wachstum wird bei Zusatz von 5% Methanol zum Minimalmedium vollständig gehemmt. Der Stamm verwertet Kohlenhydrate und Äthanol schneller als Methanol oder Milchsäure. Die Enzyme für den Methanol-Stoffwechsel scheinen jedoch konstitutiv zu sein. Die optimalen Kulturbedingungen für kurze Generationszeiten und hohe Zellausbeuten auf Methanol sind: 28°C, NH4 + als Stickstoffquelle und pH 5,0. Die Elementaranalyse ergab folgende Werte für die Zusammensetzung der Hefezellen: 42,81% C, 7,23% H und 5,54% N. Die Aminosäuren (in den Zellen) wurden mit dem Aminosäure-Analysator quantitativ bestimmt.
    Notes: Summary A yeast, Candida boidinii, isolated from soil, capable of growing on a medium containing methanol as the only carbon source is described. Biotin is required in very low concentration as a growth factor. In a study on the effect of the methanol concentration on the cell growth under favorable conditions, the cell yield was 2.3 g (dry weight) with 1% (v/v) methanol and 8.3 g with 4% methanol per 1000 ml of culture medium. However, the growth was inhibited by 5% methanol. The strain assimilated carbohydrate and ethanol faster than methanol or lactate. The enzymes for the methanol metabolism are probably constitutive. Optimal conditions for rapid growth and high cell yeild from methanol were found to be: 28°C, NH4 + as nitrogen source and pH 5.0. The cell composition was as follows: 42.81% C, 7.23% H and 5.54% N. Amino acids in the cells were analyzed by the amino acid autoanalyzer.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 105 (1975), S. 179-181 
    ISSN: 1432-072X
    Keywords: Alcohol Oxidase ; Oxidation of Formaldehyde ; Dual Substrate Specificity ; Candida boidinii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A formaldehyde oxidase activity was found in cell-free extracts of methanol-grown yeast Candida boidinii. Loss of alcohol oxidase activity in a mutant, 48, led to loss of the formaldehyde oxidase activity, indicating that the same enzyme is probably responsible for both activities. This could be demonstrated with the purified alcohol oxidase which oxidizes, besides lower primary alcohols, formaldehyde to formate. The K m value for formaldehyde is 5.7 mM. It seems that alcohol oxidase is not implicated in formaldehyde oxidation in vivo.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 90 (1973), S. 263-268 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The oxidation of formaldehyde to carbon dioxide in cell-free extracts of methanol-grown Candida boidinii has been investigated. A specific NAD-dependent formaldehyde dehydrogenase requiring reduced glutathione has been partially purified. Furthermore, a NAD-linked formate dehydrogenase was found in cell-free extracts. The synthesis of these two enzymes is induced by methanol and repressed by glucose. The possible significance of these enzymes in the energy-generating system is discussed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 117 (1978), S. 67-72 
    ISSN: 1432-072X
    Keywords: Methanol ; Degradation of microbodies ; Inactivation of enzymes ; Alcohol oxidase ; Catalase ; Candida boidinii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Degradation of microbiodies in the methanolutilizing yeastCandida boidinii was mainly studies by electron microscopical observation. The yeast cells precultured on methanol medium contained five to six microbodies per section and showed high activities of alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase. When the precultured cells were transferred into an ethanol medium the number of microbodies and concomitantly the activities of alcohol oxidase and catalase decreased. After 6 h of cultivation microbodies were hardly detected. Also the activity of alcohol oxidase was not measurable and catalase activity was reduced to one tenth, whereas the activities of formaldehyde dehydrogenase and formate dehydrogenase decreased only to about 70%. Experiments with methanol-grown cells transferred into an ethanol medium without nitrogen source indicated that the inactivation of alcohol oxidase and catalase does not require protein synthesis. However, the reappearance of these enzymes is presumably due to de novo protein synthesis as shown by experiments with cycloheximide.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-072X
    Keywords: Zymomonas mobilis ; Hopanoids ; Fatty acids ; Batch culture ; Continuous culture ; Ethanol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By thin layer chromatographic, gas-liquid chromatographic, and mass spectrometric methods 1,2,3,4-tetrahydroxypentane-29-hopane (THBH) was shown to occur in Zymomonas mobilis. This compound contributed up to 20% to the total lipids. The fatty acid pattern and the content of hopanoids (hopene, hopanol, and THBH) were determined in batch and continuous cultures. In late exponential cells from batch cultures the relative amount of palmitic acid was increased partially at the expense of cis-vaccenic acid, when the initial glucose concentrations were increased. In a batch culture, THBH reached a maximum value in the early exponential growth phase. In an anaerobic continuous culture with a low glucose feed concentration, the THBH content and the relative amount of cis-vaccenic acid were low. The contribution of both compounds increased strongly with increasing glucose feed concentrations (i.e. at higher steady-state ethanol concentrations). The same result was found with aerobic continuous cultures which produced significant amounts of acetaldehyde and acetic acid, in addition to ethanol and carbon dioxide. It was concluded that stability and permeability of the cytoplasmic membrane of the ethanol producing bacterium Z. mobilis was regulated by variations in the distribution of hopanoids and fatty acids.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 154 (1990), S. 536-543 
    ISSN: 1432-072X
    Keywords: Zymomonas mobilis ; Glucose dehydrogenase ; Pyrroloquinoline quinone ; Ubiquinone ; Electron transport chain ; TMPD oxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The interaction of the membrane-bound glucose dehydrogenase from the anaerobic but aerotolerant bacterium Zymomonas mobilis with components of the electron transport chain has been studied. Cytoplasmic membranes showed reduction of oxygen to water with the substrates glucose or NADH. The effects of the respiratory chain inhibitors piericidin, capsaicin, rotenone, antimycin, myxothiazol, HQNO, and stigmatellin on the oxygen comsumption rates in the presence of NADH or glucose as substrates indicated that a complete and in the most parts identical respiratory chain is participating in the glucose as well as in the NADH oxidation. Furthermore, the presence of coenzyme Q10 (ubiquinone 10) in Z. mobilis was demonstrated. Extraction from and reincorporation of the quinone into the membranes revealed that ubiquinone is essential for the respiratory activity with glucose and NADH. In addition, a membrane-associated tetramethyl-p-phenylene-diamine-oxidase activity could be detected in Z. mobilis.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 159 (1993), S. 197-199 
    ISSN: 1432-072X
    Keywords: Zymomonas mobilis ; Pyruvate dehydrogenase multienzyme complex ; Anaerobic formation of acetyl-CoA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the gram negative, obligately ethanologenic bacterium Zymomonas mobilis a pyruvate dehydrogenase complex was identified and the complex was enriched from cell extracts. This multienzyme complex is responsible for acetyl-CoA biosynthesis from pyruvate. No activities of related multienzyme complexes, 2-ketoglutarate dehydrogenase and branched chain keto acid dehydrogenase, could be detected.
    Type of Medium: Electronic Resource
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