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1.
The polyhydroxylated silane network of a sol-gel protected immobilised Saccharomyces cerevisiae against the effects of five organic solvents. The viability of immobilised yeast directly correlated with the logarithm of the partition coefficient of the solvent in an octanol/water two phase system increasing the decimal reduction time (D) and reaching the maximum with octanol, the most hydrophobic solvent assayed. The D value increased from 0.16 min for free yeast to 1.9 and to 22 min for immobilised yeast exposed to ethanol and 1-octanol respectively. 相似文献
2.
Ethanol production from xylose in engineered Saccharomyces cerevisiae strains: current state and perspectives 总被引:1,自引:0,他引:1
Akinori Matsushika Hiroyuki Inoue Tsutomu Kodaki Shigeki Sawayama 《Applied microbiology and biotechnology》2009,84(1):37-53
Bioethanol production from xylose is important for utilization of lignocellulosic biomass as raw materials. The research on
yeast conversion of xylose to ethanol has been intensively studied especially for genetically engineered Saccharomyces cerevisiae during the last 20 years. S. cerevisiae, which is a very safe microorganism that plays a traditional and major role in industrial bioethanol production, has several
advantages due to its high ethanol productivity, as well as its high ethanol and inhibitor tolerance. However, this yeast
cannot ferment xylose, which is the dominant pentose sugar in hydrolysates of lignocellulosic biomass. A number of different
strategies have been applied to engineer yeasts capable of efficiently producing ethanol from xylose, including the introduction
of initial xylose metabolism and xylose transport, changing the intracellular redox balance, and overexpression of xylulokinase
and pentose phosphate pathways. In this review, recent progress with regard to these studies is discussed, focusing particularly
on xylose-fermenting strains of S. cerevisiae. Recent studies using several promising approaches such as host strain selection and adaptation to obtain further improved
xylose-utilizing S. cerevisiae are also addressed. 相似文献
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Papaemmanouil V Georgogiannis N Plega M Lalaki J Lydakis D Dimitriou M Papadimitriou A 《Anaerobe》2011,(6):298-299
Saccharomyces cerevisiae is an ascomycetous yeast, that is traditionally used in wine bread and beer production. Vaginitis caused by S. cerevisiae is rare.The aim of this study was to evaluate the frequency of S. cerevisiae isolation from the vagina in two groups of women and determined the in vitro susceptibility of this fungus.
Subjects and methods
Vaginal samples were collected from a total of262 (asymptomaticandsymptomatic) women with vaginitis attending the centre of family planning of General hospital ofPiraeus. All blastomycetes that isolated from the vaginal samples were examined for microscopic morphological tests and identified by conventional methods: By API 20 C AUX and ID 32 C (Biomerieux). Antifungal susceptility testing for amphotericin B,fluconazole itraconazole,voriconazole, posaconazole and caspofungin was performed by E -test (Ab BIODIKS SWEDEN) against S. cerevisiae.Results
A total of 16 isolates of S. cerevisiae derived from vaginal sample of the referred women, average 6.10%. Susceptibility of 16 isolates of S. cerevisiae to a variety of antimycotic agents were obtained. So all isolates of S. cerevisiae were resistant to fluconazole, posaconazole and intraconazole, but they were sensitive to voriconazole caspofungin and Amphotericin B which were found sensitive (except 1/16 strains). None of the 16 patients had a history of occupational domestic use of baker’s yeast.Conclusions
Vaginitis caused by S. cerevisiae occur, is rising and cannot be ignored. Treatment of Saccharomyces vaginitis constitutes a major challenge and may require selected and often prolonged therapy. 相似文献5.
Establishment of a xylose metabolic pathway in an industrial strain of Saccharomyces cerevisiae 总被引:3,自引:0,他引:3
To produce an industrial strain of Saccharomyces cerevisiae that metabolizes xylose, we constructed a rDNA integration vector and YIp integration vector, containing the xylose-utilizing genes, XYL1 and XYL2, which encode xylose reductase (XR) and xylitol dehydrogenase (XDH) from Pichia stipitis, and XKS1, which encodes xylulokinase (XK) from S. cerevisiae, with the G418 resistance gene KanMX as a dominant selectable marker. The rDNA results in integration of multiple copies of the target genes. The industrial stain of S. cerevisiae NAN-27 was transformed with the two integration vectors to produce two recombinant strains, S. cerevisiae NAN-127 and NAN-123. Upon transformation, multiple copies of the xylose-utilizing genes were integrated into the genome rDNA locus of S. cerevisiae. Strain NAN-127 consumed twice as much xylose and produced 39% more ethanol than the parent strain, while NAN-123 consumed 10% more xylose and produced 10% more ethanol than the parent strain over 94 h. 相似文献
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Saccharomyces cerevisiae was grown in a chemostat under high glucose conditions (up to 300 g l–1). The results support the view that higher glucose feed favors higher ethanol production regardless of the existence of osmotic stress. A low glucose utilization and yield coefficient provides an opportunity to improve continuous fermentation performance in the fuel alcohol industry. The possibility exists of reusing yeast cells and subsequently lower operating costs, and by using an optimal glucose feeding concentration between 100 and 200 g l–1. 相似文献
8.
Development of novel carrier using natural zeolite and continuous ethanol fermentation with immobilized Saccharomyces cerevisiae in a bioreactor 总被引:1,自引:0,他引:1
Sho Shindo Susumu Takata Haruo Taguchi Noboru Yoshimura 《Biotechnology letters》2001,23(24):2001-2004
A natural zeolite, easily vitrified and blown at 1300 °C with a high porosity and diam. of 5–100 m, was used to immobilize Saccharomyces cerevisiae at 3.6 × 108 cells ml–1 carrier. When the abilities of natural zeolite carrier were compared with glass beads, the capacity for immobilization and alcohol fermentation activity were, respectively, 2-fold higher and 1.2-fold higher than that of glass beads. Continuous alcohol fermentation was stable for over 21 d without breakage of the carrier. 相似文献
9.
K. S. Karthikeyan H. Polasa K. Sivarama Sastry Gopal Reddy 《Indian journal of microbiology》2008,48(3):397-400
Saccharomyces cerevisiae which cannot utilize lysine as a sole nitrogen source is shown to metabolize a Lysine 3 Cr3+ (1:1) complex synthesized, as a combined nitrogen and carbon source. It induces rapid uptake of lysine and prevents loss
of viability, in contrast with free lysine. That complexation with trivalent chromium has the effect of profoundly influencing
intracellular distribution and metabolism of the liganded amino acid is demonstrated. 相似文献
10.
Chromium uptake bySaccharomyces cerevisiae and isolation of glucose tolerance factor from yeast biomass 总被引:2,自引:0,他引:2
Vlatka Gulan Zetic Vesna Stehlik-Tomas Slobodan Grba Lavoslav Lutilsky Damir Kozlek 《Journal of biosciences》2001,26(2):217-223
Fermentations with yeastSaccharomyces cerevisiae in semiaerobic and in static conditions with the addition of chromic chloride into the used molasses medium were analysed.
It was proved that the addition of optimal amounts of CrCl3 into the basal medium enhanced the kinetics of alcohol fermentations. The addition of 200 mg/l CrCl3 into the medium stimulated both the yeast growth and the ethanol production in all experimental conditions. On the other
hand, the results showed that Cr3+ ions were incorporated into yeast cells during fermentation. Under these conditions the accumulation of Cr3+ ions was performed by yeast cells during the exponential growth phase, and with enriched amounts of 30–45 (μg/gd.m. of cells.
Yeast biomass enriched with chromium ions was extracted with 01 mol/l NH4OH assuming that the extracts had the glucose tolerance factor (GTF). Then the extracts were passed through a gel-filtration
column in order to isolate and purify the GTF. The presence of GTF in the purified fractions was determined by measuring the
absorbance at 260 nm.
It is evident from the obtained results that the added purified fractions enhanced the rates of CO2 production as well as the glucose utilization during alcoholic fermentation. As expected, the enhancement of both rates depended
on the amounts of extracts added to the fermentation substrate. Thus, it is evident that purified extracts contained the GTF
compound, and that Cr3+ ions were bonded to the protein molecule. 相似文献
11.
Plasma-Membrane lipid composition and ethanol tolerance inSaccharomyces cerevisiae 总被引:25,自引:0,他引:25
Populations of cells suspended anaerobically in buffered (pH 4.5) M ethanol remained viable to a greater extent when their plasma membranes were enriched in linoleyl rather than oleyl residues irrespective of the nature of the sterol enrichment. However, populations with membranes enriched in ergosterol or stigmasterol and linoleyl residues were more resistant to ethanol than populations enriched in campesterol or cholesterol and linoleyl residues. Populations enriched in ergosterol and cetoleic acid lost viability at about the same rate as those enriched in oleyl residues, while populations grown in the presence of this sterol and palmitoleic acid were more resistant to ethanol. Suspending cells in buffered ethanol for up to 24 h did not lower the ethanol concentration. 相似文献
12.
Invertase liberation from Saccharomyces cerevisiae was detected after application of series of rectangular millisecond electric pulses. Maximal yield (60% from the activity in crude extract) was achieved within 8 h after pulsation. As shown by staining SDS-PAGE for invertase activity, the main part of liberated enzyme is a high molecular weight periplasmic invertase. 相似文献
13.
A. Hasilik 《Archives of microbiology》1974,101(1):295-301
The activity of chitin synthase extracted from whole cells of Saccharomyces cerevisiae shows reproducible changes during the course of batch cultivation. During exponential growth 5–10% of the enzyme occurs in the active form, whereas in the stationary phase no active enzyme can be detected. Of three yeast proteinases, A, B and C, only B is able to activate pre-chitin synthase and inactivate chitin synthase. A new model of the regulation is presented which accounts for the specific location as well as for termination of chitin synthesis during the budding cycle.These results were reported at the 4th International Symposium on Yeasts in Vienna, July 1974, and are part of doctoral thesis by A.H., University Freiburg (1974). 相似文献
14.
Saccharomyces cerevisiae immobilised in calcium pectate gel optimally fermented honey mash to mead with a beads/medium ratio of 1:3, at 30 °C with `Vitamon Ultra' salt as the best commercial nitrogen/nutrient source. In continuous fermentation using a two-column system, the overall ethanol production rate was 5.7 g l–1 h–1. 相似文献
15.
Summary Baker's yeast (Saccharomyces cerevisiae) was immobilized in gels made of prepolymerized, linear, water soluble polyacrylamide, partially substituted with acylhydrazide groups. Gelation was effected by the addition of controlled amounts of dialdehydes (e.g. glyoxal). The immobilized yeasts retained full glycolytic activity. Moreover, the entrapped cells were able to grow inside the chemically corsslinked gel during continuous alcohol production. Glyoxal was found to be the most favourable crosslinking agent for this system. the system employed allowed for the free exchange of substrate and products. The gel surrounding the entrapped cells had no effect on temperature stability profile. On the other hand, substantial enhancement in survival of cells in presence of high ethanol concentrations was recorded for the entrapped yeast. The capability of the immobilized yeast to carry out continuous conversion of glucose to ethanol was demonstrated. 相似文献
16.
Although suggested in some studies, the mutagenic effect of freezing has not been proved by induction and isolation of mutants. Using a well-defined genetic model, we supply in this communication evidence for the mutagenic effect of freezing on mitochondrial DNA (mtDNA) of the yeast Saccharomyces cerevisiae. The cooling for 2 h at +4 degrees C, followed by freezing for 1 h at -10 degrees C and 16 h at -20 degrees C resulted in induction of respiratory mutations. The immediate freezing in liquid nitrogen was without mutagenic effect. The study of the stepwise procedure showed that the induction of respiratory mutants takes place during the freezing at -10 and -20 degrees C of cells pre-cooled at +4 degrees C. The genetic crosses of freeze-induced mutants evidenced their mitochondrial rho- origin. The freeze-induced rho- mutants are most likely free of simultaneous nuclear mutations. The extracellular presence of cryoprotectants did not prevent the mutagenic effect of freezing while accumulation of cryoprotectors inside cells completely escaped mtDNA from cryodamage. Although the results obtained favor the notion that the mutagenic effect of freezing on yeast mtDNA is due to formation and growth of intracellular ice crystals, other reasons, such as impairment of mtDNA replication or elevated levels of ROS production are discussed as possible explanations of the mutagenic effect of freezing. It is concluded that: (i) freezing can be used as a method for isolation of mitochondrial mutants in S. cerevisiae and (ii) given the substantial development in cryopreservation of cells and tissues, special precautions should be made to avoid mtDNA damage during the cryopreservation procedures. 相似文献
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18.
Yeast (1–3) glucan synthetase is stimulated and stabilized by EDTA. Sucrose protects the enzyme from selfinactivaton. Preincubation of cell free extracts at low sucrose concentrations indicates a slow transition of the enzyme towards dissociation. Transition kinetics at 30° C and 0° C in the presence and in the absence of sucrose are interpreted assuming that a subunit is thermolabile in the free state and that sucrose increases its stability. Magnesium is deletereous for glucan synthetase in cell-free extracts. Chaotropic agents inactivate glucan synthetase according to their capacity to solubilize and depolymerize biological compounds. Fluoride plays a special role in the activation of glucan synthetase. Its action appears to be dependent on the presence of GTP (or other nucleotides). The role of all these agents on the activity and stability of the enzyme is interpreted in a unified scheme.Abbreviations EDTA
ethylene diamine tetraacetate
- Tris
tris-(hydroxymethyl) aminomethane
- MMF
mixed membrane fraction 相似文献
19.
Temperature dependency of sexual agglutination in Saccharomyces cerevisiae was found. Of 31 strains tested, which showed normal agglutination when cultured at 25°C, 29 strains lost their sexual agglutinability when they were grown at 37°C. 相似文献
20.
A Demirci A L Pometto III K-L G Ho 《Journal of industrial microbiology & biotechnology》1997,19(4):299-304
Biofilms are natural forms of cell immobilization in which microorganisms attach to solid supports. At ISU, we have developed
plastic composite-supports (PCS) (agricultural material (soybean hulls or oat hulls), complex nutrients, and polypropylene)
which stimulate biofilm formation and which supply nutrients to the attached microorganisms. Various PCS blends were initially
evaluated in repeated-batch culture-tube fermentation with Saccharomyces cerevisiae (ATCC 24859) in low organic nitrogen medium. The selected PCS (40% soybean hull, 5% soybean flour, 5% yeast extract-salt
and 50% polypropylene) was then used in continuous and repeated-batch fermentation in various media containing lowered nitrogen
content with selected PCS. During continuous fermentation, S. cerevisiae demonstrated two to 10 times higher ethanol production in PCS bioreactors than polypropylene-alone support (PPS) control.
S. cerevisiae produced 30 g L−1 ethanol on PCS with ammonium sulfate medium in repeated batch fermentation, whereas PPS-control produced 5 g L−1 ethanol. Overall, increased productivity in low cost medium can be achieved beyond conventional fermentations using this
novel bioreactor design.
Received 20 May 1997/ Accepted in revised form 29 August 1997 相似文献