PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ale yeast”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1985

Studies on NADH (NADPH)-cytochrome c reductase (FMN-containing) from yeast. Isolation and physicochemical properties of the enzyme from top-fermenting ale yeast.

Only three major NADPH-nitrotetrazolium blue (NTB) reductases may be detected in a unique top-ale yeast (Saccharomyces cerevisiae, Narragansett strain), which appears to be of a near anaerobic type with the absence of cytochromes c and a/a3 and the presence of cytochromes P-450 and b5. Two of these three major NADPH-NTB reductases possessed NADH-NTB reductase activity; the third was specific for NADPH and was isolated in this laboratory (Tryon, E., Cress, M. C., Hamada, M., and Kuby, S. A. (1979) Arch. Biochem. Biophys. 197, 104-118) vis. NADPH-cytochrome c reductase (FAD-containing). A description of the isolation procedure is provided for one of these two NADH(NADPH)-NTB reductases, viz. NADH(NADPH)-cytochrome c reductase (FMN-containing), which accounts for about one-half of the total cyanide-insensitive menadione-activated respiration of this yeast. This NADH(NADPH)-cytochrome c reductase has been isolated from an extract of an acetone powder of the top-fermenting ale yeast, with an apparent purification of more than 67-fold and a final specific activity of 0.41 and 0.31 mumol/min/mg for NADH- and NADPH-dependent reduction, respectively. The isolated enzyme proved to be homogeneous by electrophoresis on cellulose acetate and on polyacrylamide gels. It had a pI of 5.25 (at gamma/2 = 0.05) and a molecular size under nondenaturing conditions (as determined by chromatography on Sephadex G-100 and Sephacryl S-200) of 70,000 daltons. On denaturation, the enzyme dissociated into two similar, if not identical, subunits which possessed a molecular weight of 34,000 by sodium dodecyl sulfate/urea-polyacrylamide gel electrophoresis and a weight average molecular weight of 35,000 by sedimentation equilibrium in the presence of 4.0 M guanidinium chloride. The absorbance spectrum of NADH(NADPH)-cytochrome c reductase (FMN-containing) showed three maxima at 464, 383, and 278 nm, with extinction coefficients of 9.88, 9.98, and 64.6 mM-1 cm-1, respectively. The reductase, as isolated, contained 0.63 mol of FMN/34,000-dalton subunit, with no metals and one sulfhydryl group/subunit. Its amino acid composition is reported herein. Anaerobic titrations with dithionite or NAD(P)H revealed a two-electron reduction of FMN, with no spectrally observable semiquinone intermediates.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acids↗
PubMed1986

Studies on NADH(NADPH)-cytochrome c reductase (FMN-containing) from yeast: steady-state kinetic properties of the flavoenzyme from top-fermenting ale yeast.

A study of the steady-state kinetics of NADH(NADPH)-cytochrome c reductase (FMN-containing) from ale yeast (M. S. Johnson and S. A. Kuby (1985) J. Biol. Chem. 260, 12341-12350) has led to a postulated three-substrate random-ordered hybrid mechanism, where NAD(P)H and FMN add randomly and very likely in a steady-state fashion, followed by an ordered addition of cytochrome c. Kinetic parameters have been derived from this mechanism. Arrhenius plots showed large differences between NADH and NADPH, as the substrate-reductant. Menadione accelerated cytochrome c reduction and also O2 uptake, but vitamin K1 and coenzyme Q10 were ineffective as electron mediators, possibly as a result of their insolubility. With NADPH as the substrate-reductant, the order of the rate of reduction of electron acceptors was ferricyanide greater than DCIP greater than cytochrome c greater than oxygen; with menadione, the specificity sequence was cytochrome c greater than ferricyanide greater than DCIP greater than oxygen. With NADH, the order was ferricyanide greater than cytochrome c greater than oxygen greater than DCIP, which changed to cytochrome c greater than ferricyanide greater than oxygen greater than DCIP on addition of menadione. Cytochrome b5 was also reduced in the absence of oxygen. No transhydrogenase activity was observed, but the reduced thionicotinamide analogs of NADH and NADPH acted as substrates. Superoxide dismutase inhibited cytochrome c reduction in air by 50%, but O2-. was not necessary for cytochrome c reduction, as evidenced by the increase in rate in the absence of O2. The product of the reaction with oxygen appeared to be H2O2.

Catalysis↗
PubMed1984

Studies on NADPH-cytochrome c reductase. II. Steady-state kinetic properties of the crystalline enzyme from ale yeast.

From a study of the steady-state kinetics (at pH 7.6, 30 degrees C) of the reduction of cytochrome c, a 'ping-pong' mechanism may be postulated for the crystalline NADPH-cytochrome c reductase from ale yeast, Saccharomyces cerevisiae [1], a result derivable from a three-substrate ordered system with a rapid equilibrium random sequence in substrates, NADPH and FAD, followed by reactions of the third substrate, Cyt C3+. On this basis, estimates for the kinetic parameters were made together with the inhibitor dissociation constants for NADP+ (competitive with respect to NADPH as variable substrate, but noncompetitive with respect to cytochrome c3+ as the variable substrate). A noncompetitive type of inhibition was also found for cytochrome c2+ with NADPH as variable substrate, in confirmation of the proposed mechanism. With 2,6-dichloroindophenol as the acceptor, in place of cytochrome c3+, a value for KNADPH could be estimated which agreed with that estimated above, with cytochrome c3+ as the acceptor, again, in confirmation of the postulated mechanism. The reactions with molecular O2 catalyzed by the enzyme with NADPH as the reductant have been studied polarographically, and its Km for O2 estimated to be about 0.15 mmol/l at pH 7.6, 25 degrees C. The product of the reaction appears to be H2O2, which acts as a noncompetitive inhibitor for NADPH (Ki = 0.5 mmol/l), and tentatively an enzyme ternary complex containing oxygen and FADoh (semiquinone of FAD) may be assumed to be the kinetically important intermediate, which may be postulated to be in quasi-equilibrium with an enzyme ternary complex containing Oo2 (superoxide) and FAD.

Kinetics↗
PubMed2004

Two-dimensional protein map of an "ale"-brewing yeast strain: proteome dynamics during fermentation.

The first protein map of an ale-fermenting yeast is presented in this paper: 205 spots corresponding to 133 different proteins were identified. Comparison of the proteome of this ale strain with a lager brewing yeast and the Saccharomyces cerevisiae strain S288c confirmed that this ale strain is much closer to S288c than the lager strain at the proteome level. The dynamics of the ale-brewing yeast proteome during production-scale fermentation was analysed at the beginning and end of the first and the third usage of the yeast (called generation in the brewing industry). During the first generation, most changes were related to the switch from aerobic propagation to anaerobic fermentation. Fewer changes were observed during the third generation but certain stress-response proteins such as Hsp26p, Ssa4p and Pnc1p exhibited constitutive expression in subsequent generations. The ale brewing yeast strain appears to be quite well adapted to fermentation conditions and stresses.

Alcoholic Beverages↗
PubMed2004

Carbohydrate carbon sources induce loss of flocculation of an ale-brewing yeast strain.

AIMS: To identify the nutrients that can trigger the loss of flocculation under growth conditions in an ale-brewing strain, Saccharomyces cerevisiae NCYC 1195. METHODS AND RESULTS: Flocculation was evaluated using the method of Soares, E.V. and Vroman, A. [Journal of Applied Microbiology (2003) 95, 325]. Yeast growth with metabolizable carbon sources (glucose, fructose, galactose, maltose or sucrose) at 2% (w/v), induced the loss of flocculation in yeast that had previously been allowed to flocculate. The yeast remained flocculent when transferred to a medium containing the required nutrients for yeast growth and a sole nonmetabolizable carbon source (lactose). Transfer of flocculent yeast into a growth medium with ethanol (4% v/v), as the sole carbon source did not induce the loss of flocculation. Even the addition of glucose (2% w/v) or glucose and antimycin A (0.1 mg l(-1)) to this culture did not bring about loss of flocculation. Cycloheximide addition (15 mg l(-1)) to glucose-growing cells stopped flocculation loss. CONCLUSIONS: Carbohydrates were the nutrients responsible for stimulating the loss of flocculation in flocculent yeast cells transferred to growing conditions. The glucose-induced loss of flocculation required de novo protein synthesis. Ethanol prevented glucose-induced loss of flocculation. This protective effect of ethanol was independent of the respiratory function of the yeast. SIGNIFICANCE AND IMPACT OF THE STUDY: This work contributes to the elucidation of the role of nutrients in the control of the flocculation cycle in NewFlo phenotype yeast strains.

Antifungal Agents↗
PubMed1996

Strain-dependent variation in the NADH-dependent diacetyl reductase activities of larger- and alebrewing yeasts.

Significant differences were observed in the zymogram patterns of NAD(+)-dependent ethanol dehydrogenase and acetoin dehydrogenase activity in seven strains of brewer's yeast examined by non-denaturing PAGE. Bottom-fermenting (lager) strains contained quite different activity bands of acetoin dehydrogenase activity compared with top-fermenting (ale) strains. These differences were confirmed when cell-free extracts of ale yeasts were heated at 55 degrees C. This destroyed most of the diacetyl reductase activity, while leaving acetaldehyde reductase and other reductase activities unaffected. In contrast, heating cell-free extracts of lager yeasts at 55 degrees C inactivated diacetyl reductase activity and the other reductase activities at the same rate, and more slowly than with ale strains. Similar distinctions between the two types of yeast could be made by examining the effect of heat on the ratio (activity of the various substrates with NADH as electron donor)/(activity with reduced acetylpyridine-adenine dinucleotide as electron donor). The data show that the acetoin dehydrogenase/diacetyl reductase enzyme present in ale-yeast strains differs in mobility and heat-stability from that of larger strains, and that both can be distinguished from the major alcohol dehydrogenase activity bands.

Acetoin Dehydrogenase↗
PubMed2003

Use of novel assays to indicate that O-esters and S-esters are produced by the same enzyme in brewing yeast.

Ethanol- and methanethiol-dependent removal of acetyl-CoA by crude extracts of ale yeast has been monitored using a decrease in OD232. Activity has also been detected in these extracts after fractionation on polyacrylamide gels, in this case using a novel assay in which the coenzyme A produced in the reaction is linked via DCPIP reduction to color formation from nitroblue tetrazolium. Ethanol- and methanethiol-dependent activities migrate identically on such gels, and only one band of color formation was observed. Furthermore they displayed closely similar sensitivity to heating at 40 degrees C and 60 degrees C and pH optima, with activity maximal at pH 7.5. It is likely that a single enzyme is responsible for the formation of O-esters and S-esters in yeast. Initial kinetic studies indicate that methanethiol has higher affinity for the enzyme than has ethanol and a higher maximum velocity. However, the enzyme has a much lower Km for acetyl-CoA, suggesting that the alcohol or thiol substrate is the more likely substrate to be limiting.

Acetyl Coenzyme A↗
PubMed2005

Characterization and functional analysis of the MAL and MPH Loci for maltose utilization in some ale and lager yeast strains.

Maltose and maltotriose are the major sugars in brewer's wort. Brewer's yeasts contain multiple genes for maltose transporters. It is not known which of these express functional transporters. We correlated maltose transport kinetics with the genotypes of some ale and lager yeasts. Maltose transport by two ale strains was strongly inhibited by other alpha-glucosides, suggesting the use of broad substrate specificity transporters, such as Agt1p. Maltose transport by three lager strains was weakly inhibited by other alpha-glucosides, suggesting the use of narrow substrate specificity transporters. Hybridization studies showed that all five strains contained complete MAL1, MAL2, MAL3, and MAL4 loci, except for one ale strain, which lacked a MAL2 locus. All five strains also contained both AGT1 (coding a broad specificity alpha-glucoside transporter) and MAL11 alleles. MPH genes (maltose permease homologues) were present in the lager but not in the ale strains. During growth on maltose, the lager strains expressed AGT1 at low levels and MALx1 genes at high levels, whereas the ale strains expressed AGT1 at high levels and MALx1 genes at low levels. MPHx expression was negligible in all strains. The AGT1 sequences from the ale strains encoded full-length (616 amino acid) polypeptides, but those from both sequenced lager strains encoded truncated (394 amino acid) polypeptides that are unlikely to be functional transporters. Thus, despite the apparently similar genotypes of these ale and lager strains revealed by hybridization, maltose is predominantly carried by AGT1-encoded transporters in the ale strains and by MALx1-encoded transporters in the lager strains.

Base Sequence↗
PubMed2003

Biotransformation of hop aroma terpenoids by ale and lager yeasts.

Terpenoids are important natural flavour compounds, which are introduced to beer via hopping. It has been shown recently that yeasts are able to biotransform some monoterpene alcohols. As a first step towards examining whether yeasts are capable of altering hop terpenoids during the brewing of beer, we investigated whether they were transformed when an ale and lager yeast were cultured in the presence of a commercially available syrup. Both yeasts transformed the monoterpene alcohols geraniol and linalool. The lager yeast also produced acetate esters of geraniol and citronellol. The major terpenoids of hop oil, however, were not biotransformed. Oxygenated terpenoids persisted much longer than the alkenes.

Acyclic Monoterpenes↗
PubMed1996

Characteristics of maltose transporter activity in an ale and large strain of the yeast Saccharomyces cerevisiae.

Kinetic studies on maltose uptake by ale and larger yeasts showed lower Km and higher Vmax values than for laboratory yeasts. Eadie-Hofstee plots were biphasic and inhibition by sulphydryl reagents was consistent with low affinity uptake by a specific transporter rather than by non-specific adsorption. High affinity maltose transport by both strains was inhibited by galactose, CCCP, 2, 4,-DNP and NEM. In contrast, glucose and pCMBS inhibited high affinity transport by the ale yeast but not by the larger yeast. In the case of pCMBS the difference could result from a single amino acid change in the maltose transporter.

2,4-Dinitrophenol↗
PubMed1999

Multiple alpha-glucoside transporter genes in brewer's yeast.

Maltose and maltotriose are the two most abundant fermentable sugars in brewer's wort, and the rate of uptake of these sugars by brewer's yeast can have a major impact on fermentation performance. In spite of this, no information is currently available on the genetics of maltose and maltotriose uptake in brewing strains of yeast. In this work, we studied 30 brewing strains of yeast (5 ale strains and 25 lager strains) with the aim of examining the alleles of maltose and maltotriose transporter genes contained by them. To do this, we hybridized gene probes to chromosome blots. Studies performed with laboratory strains have shown that maltose utilization is conferred by any one of five unlinked but highly homologous MAL loci (MAL1 to MAL4 and MAL6). Gene 1 at each locus encodes a maltose transporter. All of the strains of brewer's yeast examined except two were found to contain MAL11 and MAL31 sequences, and only one of these strains lacked MAL41. MAL21 was not present in the five ale strains and 12 of the lager strains. MAL61 was not found in any of the yeast strains. In three of the lager strains, there was evidence that MAL transporter gene sequences occurred on chromosomes other than those known to carry MAL loci. Sequences corresponding to the AGT1 gene, which encodes a transporter of several alpha-glucosides, including maltose and maltotriose, were detected in all but one of the yeast strains. Homologues of AGT1 were identified in three of the lager strains, and two of these homologues were mapped, one to chromosome II and the other to chromosome XI. AGT1 appears to be a member of a family of closely related genes, which may have arisen in brewer's yeast in response to selective pressure.

Journal Article↗
PubMed2025

Quorum sensing in Saccharomyces cerevisiae brewing strains: effects of 2-phenylethanol on proteomic, lipidomic, and metabolomic profile.

Quorum sensing (QS) is a known mechanism by which microbial populations adjust gene expression and coordinate community-wide social behaviors based on the proximate population density. This regulatory system has garnered significant interest in both scientific research and the food industry. However, a central question remains whether industrial strains of Saccharomyces cerevisiae, the yeast species predominantly utilized in brewing, employ quorum signalling mechanisms similar to those observed in laboratory strains and other fungi. Despite the potential relevance of microbial social behavior regulators to brewing practices, studies examining QS in Saccharomyces spp. are limited. In this investigation, three industrial brewing strains of S. cerevisiae were cultivated on SLAD (nitrogen-restrictive) and SHAD (nitrogen-sufficient) agar media supplemented with 200 μM of the aromatic alcohol 2-phenylethanol (2-PE) over 72 h at 24°C. Subsequent analyses of the harvested biomass included proteomic, lipidomic, and metabolomic assessments. Results indicated that two of the industrial strains showed minimal differences in their profiles upon exposure to 2-PE, while the third strain exhibited significant differences. These findings imply that the impact of the QS molecule 2-PE on the proteome, lipidome, and metabolome of industrial S. cerevisiae may be strain-specific rather than universally applicable to the species.

Quorum Sensing↗
PubMed2003

Effect of different starvation conditions on the flocculation of Saccharomyces cerevisiae.

AIMS: To study the effect of different starvation conditions on the flocculation of an ale brewing yeast of Saccharomyces cerevisiae NCYC 1195. METHODS AND RESULTS: Flocculation was assessed by a micro-flocculation technique (Soares and Mota 1997). Carbon-starved cells of a NewFlo phenotype strain did not lose flocculation during a 48 h period. Cells incubated only in the presence of fermentable carbon sources (glucose, galactose and maltose at 2%, w/v), showed a progressive flocculation loss. The incubation of cells in 4% (v/v) ethanol did not induce a flocculation loss. The simultaneous incubation of cells in the presence of 2% (w/v) glucose and 15 microg ml(-1) cycloheximide hindered flocculation loss. The presence of 0.1 mmol l(-1) PMSF or 10 mmol l-1 EDTA prevented partially or completely, respectively, the loss of flocculation in the presence of glucose. CONCLUSIONS: Fermentable sugars induced a flocculation loss, which seems to require de novo protein synthesis and the involvement of different proteases. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings reported here contribute to the elucidation of the role of nutrients on the physiological control of yeast flocculation.

Carbon↗
PubMed1993

Polymorphism of 2-microns plasmids in industrial strains of Saccharomyces cerevisiae.

Restriction fragment length polymorphism (RFLP) analyses of industrial Saccharomyces yeast DNA have identified eight 2-microns plasmid variants that fall into two distinct types. Type-I plasmids are of unique form, whereas type-II plasmids exist in seven distinct RFLP forms. Only two different 2-microns variants were observed in 35 bakers' strains analysed. One variant was the unique type-I whereas the second variant represents an ancestral form of the type-II plasmid. Sixteen of nineteen wine yeasts carried a distinctive type-II plasmid with a homologous STB repeat whereas ale and lager yeasts had a wide range of type-II variants. Relative to nuclear and mtDNA, 2-microns polymorphism is less diverse and not diagnostic for a specific strain. This 2-microns DNA polymorphism is a convenient and useful addendum to nuclear and mtDNA RFLP analyses but cannot serve as the sole marker for strain identification. A tentative phylogeny of industrial S. cerevisiae yeasts is suggested with origins in bakers' yeast carrying the ancestral type-II form.

DNA, Fungal↗
PubMed1998

Differentiation of brewing yeast strains by pyrolysis mass spectrometry and Fourier transform infrared spectroscopy.

Two rapid spectroscopic approaches for whole-organism fingerprinting--pyrolysis mass spectrometry (PyMS) and Fourier transform infrared spectroscopy (FT-IR)--were used to analyse 22 production brewery Saccharomyces cerevisiae strains. Multivariate discriminant analysis of the spectral data was then performed to observe relationships between the 22 isolates. Upon visual inspection of the cluster analyses, similar differentiation of the strains was observed for both approaches. Moreover, these phenetic classifications were found to be very similar to those previously obtained using genotypic studies of the same brewing yeasts. Both spectroscopic techniques are rapid (typically 2 min for PyMS and 10 s for FT-IR) and were shown to be capable of the successful discrimination of both ale and lager yeasts. We believe that these whole-organism fingerprinting methods could find application in brewery quality control laboratories.

Beer↗
PubMed1996

Analysis of production brewing strains of yeast by DNA fingerprinting.

Production brewing strains of the yeast Saccharomyces cerevisiae were analysed by DNA fingerprinting, using a Southern blotting and hybridization procedure and employing the Ty1-15 transposon as a probe. The ability to differentiate readily between strains was very dependent on the restriction enzyme used to digest the DNA prior to Southern blotting and hybridization; the enzymes EcoRI, PstI and SalI were found to be particularly useful in this respect. The method was applicable to the differentiation of both ale and lager yeasts, and was sufficiently sensitive to distinguish between very closely related strains. DNA fingerprinting by this approach confirmed, for example, that a flocculent strain isolated during a production-scale fermentation with a lager yeast was genotypically different from the parent.

Base Sequence↗
PubMed2000

Delimination of brewing yeast strains using different molecular techniques.

In general, the genetic characteristics, the phenotype and the microbial purity of the production brewing yeast strains are among the most important factors in maintaining a consistently good quality of products. Analysis of restriction fragment length polymorphism (RFLP) patterns of 18S rRNA-coding DNA was investigated to group ale and lager strains. All production brewing yeast strains showed the same RFLP pattern as the type strain and synonym type strains of S. cerevisiae, and were quite different from the type and synonym type strains of S. pastorianus. Based on these data, all production brewing yeast strains investigated in this study appeared to belong to S. cerevisiae. Electrophoretic karyotyping and random amplified polymorphic DNA (RAPD) analysis appeared to be suitable methods for distinguishing not only the type and synonym type strain of S. cerevisiae and S. pastorianus, but also the ale and the lager strains.

Beer↗