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PubMed1985

Cloning and characterization of the ethanol utilization regulon in Aspergillus nidulans.

In Aspergillus nidulans alcohol dehydrogenase (ADH) I and aldehyde dehydrogenase (AldDH) are co-inducible by acetaldehyde (Pateman et al., 1983; Sealy-Lewis and Lockington, 1984) and subject to carbon catabolite repression. The structural genes alcA and aldA are unlinked, but alcA is closely linked to the positive control gene alcR. We have obtained cDNA clones of alcA and aldA and genomic clones comprising alcA and alcR. The location of these genes in a genomic clone carrying a 13-kb insert was determined by subcloning and subsequent transformation of previously characterised point mutants. We have characterised at the physical level some large deletions encompassing both linked genes. We have shown that induction affects the level of RNA hybridisible with alcA and aldA probes. Mutations in the regulatory gene alcR, result in non-inducibility of RNA hybridisible with either probe. Thus the induction process is possibly at the level of transcription. Analogous experiments suggest that carbon catabolite repression of alcohol dehydrogenase I is equally at the level of transcription.

Alcohol Dehydrogenase↗
PubMedDate not supplied

[The role of catalases in protection of proteins against oxidation in Saccharomyces cerevisiae utilizing ethanol as a carbon source].

The content of protein carbonyls and thiobarbituric acid reactive substances (TBARS) in the wild and catalase-deficient strains of the yeast Saccharomyces cerevisiae grown in glucose and ethanol media are compared. The deficient strain cells reproduced 10.6-fold slower in ethanol-containing medium. Activity of glucose-6-phosphate dehydrogenase in YWT1 cells was 1.7-fold lower when yeast are grown in ethanol, and content of protein carbonyls was 4.7-fold higher, than when they are grown in the medium with glucose. At the same time, reproduction of the wild type cells in ethanol was 2.7-fold slower and carbonyl groups of protein content was 2-fold lower, than under cultivation in glucose. TBARS content in both strains was similar when they were grown in ethanol and in glucose. It has been supposed that catalases play a certain role in the protection of S. cerevisiae proteins against oxidative modification when they are grown on the media with glucose and ethanol.

Catalase↗
PubMedDate not supplied

[Selection of mutants of microorganisms utilizing ethanol].

Mutants of the bacteria Acinetobacter calcoaceticus 34 and Acinetobacter sp. 172 as well as of the yeast Candida requinyii 316 resistant to acetaldehyde grow better in a medium with ethanol than their parent cultures. In their specific growth rate and alcohol dehydrogenase activity, 28.7-66.7% of such mutants are superior to any clone isolated in a non-selective medium. A medium containing ethanol and acetaldehyde (0.5 to 1.0% by volume) is proposed to select and isolate highly productive mutants.

Acinetobacter↗
PubMed2006

Enhancement of pyruvate productivity in Torulopsis glabrata: Increase of NAD+ availability.

This study aimed at increasing the pyruvate productivity from a multi-vitamin auxotrophic yeast Torulopsis glabrata, by increasing the availability of NAD+. We examined two strategies for increasing availability of NAD+. To supplement nicotinic acid (NA), the precursor of NAD+; and to increase the activity of alcohol dehydrogenase integrating with addition acetaldehyde as exterior electron acceptor. The addition of 8 mg l(-1) NA to the fermentation medium resulted in a significant increase in the glucose consumption rate (48.4%) and the pyruvate concentration (29%). An ethanol-utilizing mutant WSH-13 was screened and selected after nitrosoguanidine mutagenesis of the parent strain T. glabrata CCTCC M202019. Compared with the parent strain, the alcohol dehydrogenase activity of the mutant WSH-13 increased about 110% and the mutant could utilize ethanol as the sole carbon source for growth (1.8 g l(-1) dry cell weight). When growing with glucose, the addition of 4 mg l(-1) acetaldehyde to the mutant WSH-13 culture broth led to a significant increase in the glucose consumption rate (26.3%) and pyruvate production (22.5%), but the ratio of NADH/NAD+ decreased to 0.22. Acetaldehyde did not affect the glucose and energy metabolism at high dissolved oxygen (DO) concentration. However, at lower DO concentration (20%), maintaining the acetaldehyde concentration in the mutant culture broth at 4 mg l(-1) caused an increased NAD+ concentration but a decreased NADH concentration. As a consequence, the pyruvate production rate, the pyruvate yield on glucose and the pyruvate concentration were 68, 44 and 45% higher, respectively, than the corresponding values of the control (without acetaldehyde). The strategy for increasing the glycolytic flux and the pyruvate productivity in T. glabrata by increasing the availability of NAD+ may provide an alternative approach to enhance the metabolites productivity in yeast.

Biological Availability↗
PubMed1990

Ethanol attenuates endotoxin-enhanced glucose utilization.

Ethanol (EtOH) is known to alter various aspects of cellular metabolism. Among these, the blunting of the increased rate of glucose production and utilization by the host after the administration of endotoxin may be an important factor in the increased susceptibility to infections. Therefore the present study was conducted to determine which tissues are responsible for the attenuation of the endotoxin-induced increase in whole body glucose utilization after acute EtOH administration. In vivo glucose metabolic rate (Rg) of different organs was investigated in conscious rats by the tracer 2-deoxy-D-glucose technique. Rats received a slow intravenous bolus injection of EtOH (275 mg/100 g body wt of a 20% wt/vol solution) followed by a continuous infusion (25 mg/100 g body wt) that was maintained throughout the experimental period. Thirty minutes after initiation of the EtOH treatment, Escherichia coli endotoxin (100 micrograms/100 g body wt) was administered intravenously. Time-matched control animals received an equal volume of saline. EtOH alone affected Rg only in gastrocnemius muscle (30% decrease) and adipose tissue (twofold increase). Endotoxin alone increased Rg in all tissues examined except in heart and brain. Prior administration of EtOH inhibited the endotoxin-induced increased Rg in skeletal muscle (regardless of fiber type), ileum, liver, adipose tissue, and kidney, blunted the increase in spleen and lung, and did not alter the increased Rg in skin. Brain showed a 20% decrease in Rg in response to EtOH and endotoxin administration. The EtOH-attenuated increase in glucose utilization in the macrophage-rich tissues of endotoxin-treated rats may be a reflection of an impaired capacity of these tissues to respond to infection.

Animals↗
PubMed1980

Genetic variability of alcohol dehydrogenase among Australian Drosophila species: correlation of ADH biochemical phenotype with ethanol resource utilization.

Alcohol dehydrogenase (ADH) activities, electrophoretic phenotypes, and the extent of ethanol resource utilization are compared for three groups of species distinguishable on ecological criteria: 1) the cosmopolitan species D. melanogaster, a frequent inhabitant of wineries; 2) fruit-baited species of the typically Australian subgenus Scaptodrosophila: D. lativittata, D. nitidithorax and D. howensis; and 3) Scaptodrosophila species not attracted to fermented-fruit baits being collected by sweeping in temperate rain forests (D. inornata, D. collessi) or from Hibiscus flowers (D. hibisci). D. melanogaster showed the highest levels of ADH activity and an electrophoretic polymorphism with two active allelic forms, while group 2) species showed intermediate ADH activities and polymorphisms, which were consistent with "high activity" and "low activity" allelic forms in natural populations of these species, and group 3) species showed only "low activity" forms. Ethanol resource utilization follows the same sequence, being 1 greater than 2 greater than 3 (D. howensis and D. collessi were not tested). Therefore the species considered show an association of ADH biochemical phenotype, laboratory ethanol utilization, and resources utilized.

Alcohol Oxidoreductases↗
PubMed1973

Glucose utilization and ethanolic fermentation by wild type and extrachromosomal mutants of Neurospora crassa.

Logarithmic growth rates, maximal biomass, specific glucose utilization rates, and ethanol accumulation were measured in aerobic cultures of wild type and extrachromosomal mutants of Neurospora crassa. Maximal biomass and ethanol accumulation of wild type and [mi-1] were proportional to the initial glucose concentration in the range of 2 to 10%. The specific rates of glucose utilization by the mutants were 13- to 20-fold greater than those of wild type in young cultures. The specific rates of glucose utilization by wild type, however, were increased threefold by increasing the ammonium ion concentration in the preculture medium. The suppressor gene f(+) suppressed the excessive glucose utilization and enhanced the growth rate and maximal biomass of [mi-1]. When the mutants were utilizing glucose at excessive rates, ethanol did not appear in the culture medium. Ethanol accumulation was maximum at stationary phase or thereafter, but there was little difference between the maxima of the mutants and wild type. The molar efficiency of the conversion of glucose to ethanol during the entire culture period of wild type and mutants was about 50% and, in the latter stages of fermentation, approached 100%. Replacement of ammonium ion by nitrate in the culture medium suppressed ethanol accumulation by wild type. The relationship of these results to previous observations on respiratory adaptation are discussed. We suggest that the Pasteur effect, the inhibition of fermentation by respiration, may be operative in N. crassa. Factors such as nitrogen source and concentration and oxygen tension, which may serve primarily to regulate the amount and form of respiration would, therefore, indirectly regulate fermentation. The mutants, although transiently deficient in terminal respiratory activity, do not accumulate more ethanol than wild type and, therefore, apparently do not ferment in excess to obtain additional adenosine 5'-triphosphate. We suggest that the excess activity of the alternate form of respiration of the mutants may be related to their excessive rate of glucose utilization by way of the pentose phosphate pathway and the oxidation of excess reduced nicotinamide adenine dinucleotide.

Aerobiosis↗
PubMed1975

Effect of ethanol on utilization of plasma free fatty acids for liver triacylglycerol synthesis and its relation to hepatic triacylglycerol accumulation in rats.

The effect of 3 different single doses of ethanol on the liver triacylglycerol concentration and on the metabolism of intravenously injected 14C-oleic acid in fasted rats was studied. All 3 doses (2, 3.75, and 6 g ethanol/kg body wt) caused a rapid increase in the liver triacylglycerol concentration during the first 5-6 hr after the ethanol was given. Until the plasma ethanol concentration had fallen to low values, the high liver triacylglycerol levels were raised and were independent of the ethanol dose given. The incorporation of radioactivity from intravenously injected 14C-oleic acid into liver triacylglycerols was increased over control values to the same extent in all rats given ethanol as long as the plasma ethanol concentration was above a low level. High rates of ethanol oxidation and increased utilization of plasma free fatty acids for liver triacylglycerol synthesis were closely correlated with the development and maintenance of the ethanol induced liver triacylglycerol accumulation.

Animals↗
PubMed1977

Common mechanism for the adaptive increase in hepatic ethanol and acetaldehyde metabolism due to chronic pretreatment with ethanol.

Perfused livers from ethanol pretreated rats utilized ethanol and acetaldehyde at higher rates than appropriate controls. This adaptive increase in hepatic ethanol and acetaldehyde uptake was associated with a marked (greater than 60%) increase in hepatic oxygen uptake. Ethanol uptake in both ethanol-treated and control livers was similarly sensitive to inhibition by 4-methylpyrazole, rotenone, and antimycin A. The adaptive increase in ethanol uptake was apparently specifically abolished by ouabain, an inhibitor of the sodium-plus potassium-activated ATPase. The data are consistent with the hypothesis that chronic treatment with ethanol increases ATPase activity. The ADP produced from these initiating events enters the mitochondrial space and stimulates electron transport and oxygen uptake. As a consequence of these events, a greater rate of NADH reoxidation occurs, resulting in a greater rate of production of NAD+ which stimulates ethanol oxidation via alcohol dehydrogenase and acetaldehyde oxidation via aldehyde dehydrogenase(s).

Acetaldehyde↗
PubMed2000

Ethanol effects on cardiomyocyte contractility.

Little is known about the direct cardiac effects of socially common sub-intoxication levels of ethanol. Previous studies evaluating the responses of normal cardiomyocytes to short-term ethanol exposure have utilized ethanol concentrations equivalent to extreme intoxication or lethal levels in vivo. The purpose of the present study was to investigate the contractile responses of isolated rat ventricular cardiomyocytes during exposure to relatively low concentrations of ethanol in the range 0.05-0.5% (v/v) (8.6-86 mM) under physiological conditions (3 Hz stimulation; 36 degrees C; BSA vehicle). High-speed imaging techniques were used to study the kinetics of myocyte contraction, and shortening parameters were calculated for mechanistic evaluation. The concentration-response relationship was not linear and exhibited two plateau phases, suggesting at least two mechanisms of action of ethanol on cardiomyocyte contraction. At 0.05% (8.6 mM), ethanol treatment produced a 14.4% decrease in maximum myocyte shortening. The maximum rates of cell shortening and lengthening were similarly impaired, but there was no effect on contraction cycle timing at this low concentration. At 0.30% (51 mM), ethanol reduced maximum shortening by 40.2%, prolonged excitation-contraction coupling latency and abbreviated the contraction cycle time by 38%. The inotropic modulatory effect of ethanol was exaggerated in the absence of protein in the superfusion buffer. This is the first report which identifies ethanol at 0.05% (v/v) as a modulator of cardiac contractility. Kinetic analyses indicate that the mechanism of action involves disturbance of sarcoplasmic reticulum function, and this may contribute to arrhythmogenic vulnerability - especially in an in vivo context of heightened compensatory sympathetic drive.

Animals↗
PubMed2001

[Studies on extraction process of Phyllanthus urinaria].

OBJECTIVE: To optimize the extraction process of Phyllanthus urinaria L. METHOD: The optimum extraction condition was investigated by the orthogonal design in flavonoids content as index. RESULTS: The factors influencing extraction efficiency were as follows: D > A > B> C (A: Concentration of ethanol, B: The amount of ethanol added, C: Time of extraction, D: Times of extraction). The optimum extraction condition was: extracting the drug for 3 times, every time for 2 hour, after adding 8 fold of ethanol, utilizing concentration of ethanol for 70%. CONCLUSION: The optimized process is stable and high efficient.

Chemistry, Pharmaceutical↗
PubMed2006

Continuous ethanol fermentation of cheese whey powder solution: effects of hydraulic residence time.

Continuous ethanol fermentation of cheese whey powder solution was realized using pure culture of Kluyveromyces marxianus (DSMZ 7239) at hydraulic residence times (HRT) between 12.5 and 60 h. Sugar utilization, ethanol and biomass formation were investigated as functions of HRT. Effluent sugar concentration decreased, but percent sugar utilization, ethanol and biomass concentrations increased with HRT. Ethanol productivity was maximum (0.745 gE l(-1)h(-1)) at an HRT of 43.2 h where the biomass productivity was almost minimum (0.18 gX l(-1) h(-1)). The ethanol yield coefficient was almost constant at 0.4 gE g(-1)S up to HRT of 43.2 h and the growth yield coefficient was minimum at HRT of 43.2 h. Kinetic models were developed and the constants were determined by using the experimental data.

Bioreactors↗
PubMed2001

Heterogeneity of stress gene expression and stress resistance among individual cells of Saccharomyces cerevisiae.

Knowledge of gene expression and cellular responses in microorganisms is derived from analyses of populations consisting of millions of cells. Analytical techniques that provide data as population averages fail to inform of culture heterogeneity. Flow cytometry and fluorescence techniques were used to provide information on the heterogeneity of stress-responsive gene expression and stress tolerance in individual cells within populations. A sequence of DNA encoding the heat shock and stress response elements of the Saccharomyces cerevisiae HSP104 gene was used to express enhanced green fluorescent protein (EGFP). When integrated into the genome of yeast strain W303-1A, intrinsic expression of EGFP increased about twofold as cells progressed from growth on glucose to ethanol utilization in aerobic batch cultures. Staining of cells with orange/red fluorescent propidium iodide (PI), which only enters cells that have compromised membrane integrity, revealed that the population became more tolerant to 52 degrees C heat stress as it progressed from growth on glucose and through the ethanol utilization phase of aerobic batch culture. Exposure of cultures growing on glucose to a mild heat shock (shift from 25 degrees C to 37 degrees C) resulted in significantly increased expression of EGFP in the population. However, there was heterogeneity in the intensity of fluorescence of individual cells from heat-shocked cultures, indicating variability in the strength of stress response in the clonal population. Detailed analysis of the heterogeneity showed a clear positive trend between intensity of stress response and individual cell resistance, measured in terms of PI exclusion, to heat stress at 52 degrees C. Further experiments indicated that, although the mean gene expression by a population is influenced by the genetic background, the heterogeneity among individual cells in clonal populations is largely physiologically based.

Base Sequence↗
PubMed1985

Degradative inactivation of the peroxisomal enzyme, alcohol oxidase, during adaptation of methanol-grown Candida boidinii to ethanol.

Adaptation of methanol-grown C. boidinii to ethanol-utilization in non-growing cells resulted in decreased activity of the peroxisomal enzyme alcohol oxidase. Re-appearance of alcohol oxidase activity was dependent on protein synthesis de novo. Degradation of alcohol oxidase protein was shown to parallel the decrease in activity. Adaptation of methanol-grown cells to ethanol-utilization resulted in increased absorbance due to cytochromes and decreased absorbance due to flavoprotein. Decrease in alcohol oxidase activity was associated with loss of the flavin coenzyme, FAD, from the organisms and the appearance of flavins (FAD, FMN, riboflavin) in the surrounding medium. Electron microscopic observations showed that general degradation of whole peroxisomes rather than specific loss of crystalline cores (alcohol oxidase protein) occurred during the adaptation.

Adaptation, Physiological↗
PubMed1986

Changes in proteinase activities and subcellular distribution during inactivation of alcohol oxidase in Candida boidinii.

Adaptation of methanol-grown Candida boidinii to ethanol utilization was accompanied by an increase in proteolytic activities, which behaved like known vacuolar enzymes. Degradation of alcohol oxidase protein was partially prevented by the serine proteinase inhibitor phenylmethanesulphonyl fluoride, but not by the carboxyl proteinase inhibitor pepstatin. Fractionation of cell-free extracts, by high-speed zonal centrifugation, of methanol-grown C. boidinii showed non-sedimentable and sedimentable proteolytic activities. Naturally occurring inhibitors of vacuolar proteinases were non-sedimentable. Fractionation of extracts prepared from methanol-grown cells which had been adapted to ethanol utilization for 5 h revealed significant changes in the sedimentability and distribution of proteolytic and acid phosphatase activities. These results suggest the possible involvement of a vacuolar process during alcohol oxidase degradation.

Alcohol Oxidoreductases↗
PubMed1996

Metabolic fluxes in chemostat cultures of Schizosaccharomyces pombe grown on mixtures of glucose and ethanol.

Simultaneous utilization of glucose and ethanol by the yeast Schizosaccharomyces pombe CBS 356 was studied in aerobic chemostat cultures. In glucose-limited cultures, respirofermentative metabolism occurred at growth rates above 0.16 h-1. Although Sch. pombe lacks a functional glyoxylate cycle and therefore cannot utilize ethanol as a sole carbon source, ethanol was co-consumed by glucose-limited chemostat cultures. As a result, biomass yields increased, but not up to the theoretical value [0.92 g biomass (g glucose)-1] expected if all of the acetyl-CoA produced from glucose was instead synthesized from ethanol. When ethanol accounted for more than 30% of the substrate carbon in the mixed feed, it was incompletely utilized. In mixed-substrate cultures with a saturating ethanol fraction in the feed, the increase of the biomass yield as a result of ethanol consumption was highest at low dilution rates. This was not due to an increased specific rate of ethanol consumption at low growth rates; rather, the longer residence times at low dilution rates allowed Sch. pombe to utilize a larger fraction of the available ethanol, part of which was oxidized to acetate. Activities of gluconeogenic and glyoxylate-cycle enzymes were not detected in cell-free extracts of any of the cultures. Activities of acetaldehyde dehydrogenase and acetyl-CoA synthetase were low and of the same order of magnitude as the in vivo rates of acetate activation to acetyl-CoA. The results show that ethanol is a poor substrate for Sch. pombe, even as an auxiliary energy source.

Adenosine Triphosphate↗