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  • yeast  (6)
  • fermentation  (4)
  • Yeasts  (2)
  • mitochondria  (2)
  • respiration  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Physiological characterisation of a pyruvate-carboxylase-negative Saccharomyces cerevisiae mutant in batch and chemostat cultures (1998)
    Springer
    Antonie van Leeuwenhoek 74 (1998), S. 253-263 
    Details
    ISSN: 1572-9699
    Keywords: Saccharomyces cerevisiae ; pyruvate carboxylase ; anaplerotic reactions ; sugar metabolism ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A prototrophic pyruvate-carboxylase-negative (Pyc-) mutant was constructed by deleting the PYC1 and PYC2 genes in a CEN.PK strain of Saccharomyces cerevisiae. Its maximum specific growth rate on ethanol was identical to that of the isogenic wild type but it was unable to grow in batch cultures in glucose-ammonia media. Consistent with earlier reports, growth on glucose could be restored by supplying aspartate as a sole nitrogen source. Ethanol could not replace aspartate as a source of oxaloacetate in batch cultures. To investigate whether alleviation of glucose repression allowed expression of alternative pathways for oxaloacetate synthesis, the Pyc- strain and an isogenic wild-type strain were grown in aerobic carbon-limited chemostat cultures at a dilution rate of 0.10 h-1 on mixtures of glucose and ethanol. In such mixed-substrate chemostat cultures of the Pyc- strain, steady-state growth could only be obtained when ethanol contributed 30% or more of the substrate carbon in the feed. Attempts to further decrease the ethanol content of the feed invariably resulted in washout. In Pyc- as well as in wild-type cultures, levels of isocitrate lyase, malate synthase and phospho-enol-pyruvate carboxykinase in cell extracts decreased with a decreasing ethanol content in the feed. Nevertheless, at the lowest ethanol fraction that supported growth of the Pyc- mutant, activities of the glyoxylate cycle enzymes in cell extracts were still sufficient to meet the requirement for C4-compounds in biomass synthesis. This suggests that factors other than glucose repression of alternative routes for oxaloacetate synthesis prevent growth of Pyc-mutants on glucose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001772613615
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  • 2
    Electronic Resource
    Electronic Resource
    Hydrogen peroxide as an electron acceptor for mitochondrial respiration in the yeast Hansenula polymorpha (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 7 (1991), S. 137-146 
    Details
    ISSN: 0749-503X
    Keywords: Cytochrome c peroxidase ; hydrogen peroxide ; energetics ; yeast ; anaerobic respiration ; chemostat ; mitochondria ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Chemostat cultures of a catalase-negative mutant of Hansenula polymorpha CBS 4732 were able to decompose hydrogen peroxide at a high rate. This was apparent from experiments in which yeast was grown under carbon limitation in chemostat culture on mixtures of glucose and H2O2. The enzyme responsible for H2O2 degradation is probably the mitochondrial enzyme cytochrome c peroxidase (CCP), which was present at very high activities. This enzyme was partially purified and shown to be specific for reduced cytochrome c as an electron donor; no reaction was observed with NAD(P)H. Thus, reducing equivalents for H2O2 degradation by CCP must be provided by the respiratory chain.That H2O2 can act as an electron acceptor for reducing equivalents could be confirmed with experiments in which cells were incubated with ethanol and H2O2 in the absence of oxygen. This resulted in oxidation of ethanol to equimolar amounts of acetate.Energetic aspects of mitochondrial H2O2 decomposition via CCP and the physiological function of CCP in yeasts are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320070207
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of benzoic acid on metabolic fluxes in yeasts: A continuous-culture study on the regulation of respiration and alcoholic fermentation (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 8 (1992), S. 501-517 
    Details
    ISSN: 0749-503X
    Keywords: benzoic acid: Yeasts ; Crabtree effect ; respiration ; fermentation ; mitochondria ; metabolic flux ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Addition of benzoate to the medium reservoir of glucose-limited chemostat cultures of Saccharomyces cerevisiae CBS 8066 growing at a dilution rate (D) of 0.10 h-1 resulted in a decrease in the biomass yield, and an increase in the specific oxygen uptake rate (qO2) from 2.5 to as high as 19.5 mmol g-1h-1. Above a critical concentration, the presence of benzoate led to alcoholic fermentation and a reduction in (qO2) to 13 mmol g-1h-1. The stimulatory effect of benzoate on respiration was dependent on the dilution rate: at high dilution rates respiration was not enhanced by benzoate. Cells could only gradually adapt to growth in the presence of benzoate: a pulse of benzoate given directly to the culture resulted in wash-out.As the presence of benzoate in cultures growing at low dilution rates resulted in large changes in the catabolic glucose flux, it was of interest of study the effect of benzoate on the residual glucose concentration in the fermenter as well as on the level of some selected enzymes. At D=0.10 h-1, the residual glucose concentration increased proportionally with increasing benzoate concentration. This suggests that modulation of the glucose flux mainly occurs via a change in the entracellular glucose concentration rather than by synthesis of an additional amount of carriers. Also various intracellular enzyme levels were not positively correlated with the rate of respiration. A notable exception was citrate synthase: its level increased with increasing respiration rate.Growth ofS. cerevisiae in ethanol-limited cultures in the presence of benzoate also led to very high qO2 levels of 19-21 mmol g-1h-1. During growth on glucose as well as on ethanol, the presence of benzoate coincided with an increase in the mitochondrial volume up to one quarter of the total cellular volume.Also with the Crabtree-negative yeasts Candida utilis, Kluyveromyces marxianus andHansenula polymorpha, growth in the presence of benzoate resulted in an increase in qO2 and, at high concentrations of benzoate, in aerobic fermentation. In contrast to S.Cerevisiae, the highest qO2 of these yeasts when growing at D = 0.10 h-1 in the presence of benzoate was equal to, or lower than the qO2 attainable at μmax without benzoate. Enzyme activities that were repressed by glucose in S. cerevisiae also declined in K.Marxianus when the glucose flux was increased by the presence of benzoate.The maximal aerobic fermentation rate at D = 0.10 h-1 of the Crabtree-negative yeasts at high benzoate concentrations was considerably lower than for S. cerevisiae. This is probably due to the fact that under aerobic conditions these yeasts are unable to raise the low basal pyruvate decarboxylase level: cultivation without benzoate under oxygen-limited conditions resulted in rates of alcoholic fermentation and levels of pyruvate decarboxylase comparable to those of S. cerevisiae.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320080703
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  • 4
    Electronic Resource
    Electronic Resource
    Substrate-accelerated death of Saccharomyces cerevisiae CBS 8066 under maltose stress (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 6 (1990), S. 149-158 
    Details
    ISSN: 0749-503X
    Keywords: Maltose transport ; α-glucosidase ; yeast ; chemostat ; cell death ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: When Saccharomyces cerevisiae CBS 8066 was grown under maltose limitation, two enzymes specific for maltose utilization were present: a maltose carrier, and the maltose-hydrolysing α-glucosidase. The role of these two enzymes in the physiology of S. cerevisiae was investigated in a comparative study in which Candida utilis CBS 621 was used as a reference organism.Maltose pulses to a maltose-limited chemostat culture of S. cerevisiae resulted in ‘substrate-accelerated death’. This was evident from: (1) enhanced protein release from cells: (2) excretion of glucose into the medium; (3) decreased viability. These effects were specific with respect to both substrate and organism: pulses of glucose to maltose-limited cultures of S. cerevisiae did not result in cell death, neither did maltose pulses to maltose-limited cultures of C. utilis. The maltose-accelerated death of S. cerevisiae is most likely explained in terms of an uncontrolled uptake of maltose into the cell, resulting in an osmotic burst. Our results also provide evidence that the aerobic alcoholic fermentation that occurs after pulsing sugars to sugar-limited cultures of S. cerevisiae (short-term Crabtree effect) cannot solely be explained in terms of the mechanism of sugar transport. Both glucose and maltose pulses to maltose-limited cultures triggered aerobic alcohol formation. However, glucose transport by S. cerevisiae occurs via facilitated diffusion, whereas maltose entry into this yeast is mediated by a maltose/proton symport system.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320060209
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  • 5
    Electronic Resource
    Electronic Resource
    Properties of enzymes which reduce dihydroxyacetone and related compounds in hansenula polymorpha CBS 4732 (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 4 (1988), S. 117-126 
    Details
    ISSN: 0749-503X
    Keywords: Yeasts ; dihydroxyacetone ; acetoin ; diacetyl ; acetol ; methylglyoxal, acetone ; glycerol ; 1,2-propanediol ; 2,3-butanediol ; dehydrogenase ; reductase ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Hansenula polymorpha CBS 4732 grown on a variety of substrates contained very high activities of enzymes catalyzing the NADH-linked reduction of dihydroxyacetone, acetoin, diacetyl, acetol, methylglyoxal and acetone. The enzymes catalyzing these reductions have been purified and their kinetic properties are described. Three different enzymes were found responsible for the above-mentioned activities, namely: (1) dihydroxyacetone reductase; (2) acetone reductase; and (3) alcohol dehydrogenase.So far, the physiological function of dihydroxyacetone reductase and acetone reductase is obscure. The kinetic properties of dihydroxyacetone reductase and the regulation of the synthesis of this enzyme suggest that it does not function as a glycerol dehydrogenase.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320040205
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation of alcoholic fermentation in batch and chemostat cultures of Kluyveromyces lactis CBS 2359 (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 459-469 
    Details
    ISSN: 0749-503X
    Keywords: Crabtree effect ; yeast ; biomass ; Kluyveromyces lactis ; oxygen ; pyruvate decarboxylase ; regulation ; fermentation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Kluyveromyces lactis is an important industrial yeast, as well as a popular laboratory model. There is currently no consensus in the literature on the physiology of this yeast, in particular with respect to aerobic alcoholic fermentation (‘Crabtree effect’). This study deals with regulation of alcoholic fermentation in K. lactis CBS 2359, a proposed reference strain for molecular studies. In aerobic, glucose-limited chemostat cultures (D=0·05-0·40 h-1) growth was entirely respiratory, without significant accumulation of ethanol or other metabolites. Alcoholic fermentation occurred in glucose-grown shake-flask cultures, but was absent during batch cultivation on glucose in fermenters under strictly aerobic conditions. This indicated that ethanol formation in the shake-flask cultures resulted from oxygen limitation. Indeed, when the oxygen feed to steady-state chemostat cultures (D=0·10 h-1) was lowered, a mixed respirofermentative metabolism only occurred at very low dissolved oxygen concentrations (less than 1% of air saturation). The onset of respirofermentative metabolism as a result of oxygen limitation was accompanied by an increase of the levels of pyruvate decarboxylase and alcohol dehydrogenase. When aerobic, glucose-limited chemostat cultures (D=0·10 h-1) were pulsed with excess glucose, ethanol production did not occur during the first 40 min after the pulse. However, a slow aerobic ethanol formation was invariably observed after this period. Since alcoholic fermentation did not occur in aerobic batch cultures this is probably a transient response, caused by an imbalanced adjustment of enzyme levels during the transition from steady-state growth at μ=0·10 h-1 to growth at μmax. It is concluded that in K. lactis, as in other Crabtree-negative yeasts, the primary environmental trigger for occurrence of alcoholic fermentation is oxygen limitation. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Alcoholic fermentation by ‘non-fermentative’ yeastsCentraalbureau voor Schimmelcultures, Yeast Division, Delft, The NetherlandsDedicated to Dr Nelly J. W. Kreger-van Rij. (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 2 (1986), S. 123-127 
    Details
    ISSN: 0749-503X
    Keywords: Yeasts ; fermentation ; ethanol ; Durham tube test ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: All type strains of ‘non-fermentative’ yeasts, available in the culture collection of the Centraalbureau voor Schimmelcultures, were reinvestigated for their capacity to ferment glucose in the classical Durham tube test. Although visible gas production was absent, nearly all strains produced significant amounts of ethanol under the test conditions. Under conditions of oxygen-limited growth, even strong alcoholic fermentation may occur in a number of yeasts hitherto considered as non-fermentative. Thus, shake-flask cultures of Hansenula nonfermentans and Candida silvae fermented more than half of the available sugar to ethanol. It is concluded that the taxonomic test for fermentation capacity, which relies on detection of gas formation in Durham tubes, is not reliable for a physiological classification of yeasts as fermentative and non-fermentative species.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320020208
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetics of growth and glucose transport in glucose-limited chemostat cultures of Saccharomyces cerevisiae CBS 8066 (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 5 (1989), S. 159-165 
    Details
    ISSN: 0749-503X
    Keywords: Crabtree effect ; sugar transport ; growth kinetics ; yeast ; chemostat ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The glucose transport capacity of Saccharomyces cerevisiae CBS 8066 was studied in aerobic glucose-limited chemostat cultures. Two different transport systems were encountered with affinity constants of 1 and 20 mM, respectively. The capacity of these carriers (Vmax) was dependent on the dilution rate and the residual glucose concentration in the culture. From the residual glucose concentration in the fermenter and the kinetic constants of glucose transport, their in situ contribution to glucose consumption was determined. The sum of these calculated in situ transport rates correlated well with the observed rate of glucose consumption of the culture.The growth kinetics of S. cerevisiae CBS 8066 in glucose-limited cultures were rather perculiar. At low dilution rates, at which glucose was completely respired, the glucose concentration in the fermenter was constant at 110 μM, independent of the glucose concentration in the reservoir. At high dilution rates, characterized by the occurrence of both respiration and alcoholic fermentation, the residual substrate concentration followed Monod kinetics. In this case, however, the overall affinity constant was dependent on the reservoir glucose concentration.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320050305
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  • 9
    Electronic Resource
    Electronic Resource
    Transient responses of Candida utilis to oxygen limitation: Regulation of the Kluyver effect for maltose (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 11 (1995), S. 317-325 
    Details
    ISSN: 0749-503X
    Keywords: yeast ; Candida utilis ; alcoholic fermentation ; Kluyver effect ; oxygen limitation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The facultatively fermentative yeast Candida utilis exhibits the Kluyver effect for maltose: this disaccharide is respired and assimilated but, in contrast to glucose, it cannot be fermented. To study the mechanism of the Kluyver effect, metabolic responses of C. utilis to a transition from aerobic, sugar-limited growth to oxygen-limited conditions were studied in chemostat cultures. Unexpectedly, the initial response of maltose-grown cultures to oxygen limitation was very similar to that of glucose-grown cultures. In both cases, alcoholic fermentation occurred after a lag phase of 1 h, during which glycerol, pyruvate and D-lactate were the main fermentation products. After ca. 10 h the behaviour of the maltose- and glucose-grown cultures diverged: ethanol disappeared from the maltose-grown cultures, whereas fermentation continued in steady-state, oxygen-limited cultures grown on glucose. The disappearance of alcoholic fermentation in oxygen-limited chemostat cultures growing on maltose was not due to a repression of the synthesis of pyruvate decarboxylase and alcohol dehydrogenase. The results demonstrate that the Kluyver effect for maltose in C. utilis does not reflect an intrinsic inability of this yeast to ferment maltose, but is caused by a regulatory phenomenon that affects a key enzyme in maltose metabolism, probably the maltose carrier. The observed kinetics indicate that this regulation occurs at the level of enzyme synthesis rather than via modification of existing enzyme activity.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320110404
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  • 10
    Electronic Resource
    Electronic Resource
    Metabolic responses of Saccharomyces cerevisiae CBS 8066 and Candida utilis CBS 621 upon transition from glucose limitation to glucose excess (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 4 (1988), S. 283-291 
    Details
    ISSN: 0749-503X
    Keywords: Crabtree effect ; respiration ; fermentation ; Saccharomyces ; Candida ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: When chemostat cultures of Saccharomyces cerevisiae CBS 8066 and Candida utilis CBS 621, grown under glucose limitation, were pulsed with excess glucose, both organisms initially exhibites similar rates of glucose and oxygen consumption. However, striking differences were apparent between the two yeasts with respect to the production of cell mass in the culture and metabolic excretion. Upon transition from glucose limitation excess, S. cerevisiae produced much ethanol but growth rate close to that under glucose limitation. C. utilis, on the other hand, produced little ethanol and immediately started to accumulated cell mass at a high rate. This high production rate of protein synthesis.Upon a glucose pulse both yeasts excreated pyuvate. In contrast to C. utilis. S. cerevisiae also excerted various tricarboxylic acid cycle intermediates, both under steady-state conditions and after exposure to glucose excess, These results and those of theoritical calculations on ATP flows support the hypothesis that the ethanol production as a consequences of pyruvate accumulatiion in S. cerevisiae, occuring transition from glucose limitaion to glucose excess, is caused by a limited capacity of assimilatory pathways.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320040406
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