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PubMed2001

Novel inhibitors of poly(ADP-ribose) polymerase/PARP1 and PARP2 identified using a cell-based screen in yeast.

Multicellular organisms must have means of preserving their genomic integrity or face catastrophic consequences such as uncontrolled cell proliferation or massive cell death. One response is a modification of nuclear proteins by the addition and removal of polymers of ADP-ribose that modulate the properties of DNA-binding proteins involved in DNA repair and metabolism. These ADP-ribose units are added by poly(ADP-ribose) polymerase (PARP) and removed by poly(ADP-ribose) glycohydrolase. Although budding yeast Saccharomyces cerevisiae does not possess proteins with significant sequence similarity to the human PARP family of proteins, we identified novel small molecule inhibitors against two family members, PARP1 and PARP2, using a cell-based assay in yeast. The assay was based on the reversal of growth inhibition caused by the heterologous expression of either PARP1 or PARP2. Validation of the assay was achieved by showing that the growth inhibition was relieved by a mutation in a single residue in the catalytic site of PARP1 or PARP2 or exposure of yeast to a known PARP1 inhibitor, 6(5H)-phenanthridinone. In separate experiments, when a putative protein regulator of PARP activity, human poly(ADP-ribose) glycohydrolase, was coexpressed with PARP1 or PARP2, yeast growth was restored. Finally, the inhibitors identified by screening the yeast assay are active in a mammalian PARP biochemical assay and inhibit PARP1 and PARP2 activity in yeast cell extracts. Thus, our data reflect the strength of using yeast to identify small molecule inhibitors of therapeutically relevant gene families, including those that are not found in yeast, such as PARP. The resultant inhibitors have two critical uses (a) as leads for drug development and (b) as tools to dissect cellular function.

ATP-Binding Cassette Transporters↗

PubMed1977

Steady state kinetics and binding of eukaryotic cytochromes c with yeast cytochrome c peroxidase.

1. The steady state kinetics for the oxidation of ferrocytochrome c by yeast cytochrome c peroxidase are biphasic under most conditions. The same biphasic kinetics were observed for yeast iso-1, yeast iso-2, horse, tuna, and cicada cytochromes c. On changing ionic strength, buffer anions, and pH, the apparent Km values for the initial phase (Km1) varied relatively little while the corresponding apparent maximal velocities varied over a much larger range. 2. The highest apparent Vmax1 for horse cytochrome c is attained at relatively low pH (congruent to 6.0) and low ionic strength (congruent to 0.05), while maximal activity for the yeast protein is at higher pH (congruent to 7.0) and higher ionic strength (congruent to 0.2), with some variations depending on the nature of the buffering ions. 3. Direct binding studies showed that cytochrome c binds to two sites on the peroxidase, under conditions that give biphasic kinetics. Under those ionic conditions that yield monophasic kinetics, binding occurred at only one site. At the optimal buffer concentrations for both yeast and horse cytochromes c, the KD1 and KD2 values approximate the Km1 and Km2 values. At ionic strengths below optimal, binding becomes too strong and above optimal, too weak. 4. Under ionic conditions that are optimal and give monophasic kinetics with horse cytochrome c but are suboptimal for the yeast protein, yeast cytochrome c strongly inhibits the reaction of horse cytochrome c with peroxidase, uncompetitively at one site and competitively at a second site. The appearance of the second site under monophasic conditions is interpreted as an allosteric effect of the inhibitor binding to the first site. 5. The simplest model accounting for these observations postulates two kinetically active sites on each molecule of peroxidase, a high affinity and a low affinity site, that may correspond to the free radical and the heme iron (IV) of the oxidized enzyme, respectively. Both oxidizing equivalents may be discharged at either site. Furthermore, the enzyme appears to exist as an equilibrium mixture of a high ionic strength form, EH and a low ionic strength form, EL, the former reacting optimally with yeast cytochrome c, and the latter with horse cytochrome c.

Animals↗

PubMed1992

Functional expression of plant plasma membrane H(+)-ATPase in yeast endoplasmic reticulum.

Recombinant plant plasma membrane H(+)-ATPase has been produced in a yeast expression system comprising a multicopy plasmid and the strong promoter of the yeast PMA1 gene. Western blotting with a specific monoclonal antibody showed that the plant ATPase is one of the major membrane proteins made by the transformed cells, accounting for about 1% of total yeast protein. The plant ATPase synthesized in yeast is fully active. It hydrolyzes ATP, pumps protons, and the reaction cycle involves a phosphorylated intermediate. Phosphorylation is possible from both ATP and Pi. Unlike the situation in plants, however, most of the plant ATPase is not expressed in the yeast plasma membrane. Rather, the enzyme appears to remain trapped at a very early stage of secretory pathway: insertion into the endoplasmic reticulum. This organelle was observed to proliferate in the form of stacked membranes surrounding the yeast nucleus in order to accommodate the large amount of plant ATPase produced. In this location, the plant ATPase can be purified with high yield (70 mg from 1 kg of yeast) from membranes devoid of endogenous yeast plasma membrane H(+)-ATPase. This convenient expression system could be useful for other eukaryotic membrane proteins and ATPases.

Adenosine Triphosphate↗

PubMed2004

Characterization of winemaking yeast by cell number-size distribution analysis through flow field-flow fractionation with multi-wavelength turbidimetric detection.

Yeasts are widely used in several areas of food industry, e.g. baking, beer brewing, and wine production. Interest in new analytical methods for quality control and characterization of yeast cells is thus increasing. The biophysical properties of yeast cells, among which cell size, are related to yeast cell capabilities to produce primary and secondary metabolites during the fermentation process. Biophysical properties of winemaking yeast strains can be screened by field-flow fractionation (FFF). In this work we present the use of flow FFF (FlFFF) with turbidimetric multi-wavelength detection for the number-size distribution analysis of different commercial winemaking yeast varieties. The use of a diode-array detector allows to apply to dispersed samples like yeast cells the recently developed method for number-size (or mass-size) analysis in flow-assisted separation techniques. Results for six commercial winemaking yeast strains are compared with data obtained by a standard method for cell sizing (Coulter counter). The method here proposed gives, at short analysis time, accurate information on the number of cells of a given size, and information on the total number of cells.

Fractionation, Field Flow↗

PubMed1991

Identification of a glycogen synthase phosphatase from yeast Saccharomyces cerevisiae as protein phosphatase 2A.

A glycogen synthase phosphatase was purified from the yeast Saccharomyces cerevisiae. The purified yeast phosphatase displayed one major protein band which coincided with phosphatase activity on nondenaturing polyacrylamide gel electrophoresis. This phosphatase had a molecular mass of about 160,000 Da determined by gel filtration and was comprised of three subunits, termed A, B, and C. The subunit molecular weights estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis were 60,000 (A), 53,000 (B), and 37,000 (C), indicating that this yeast glycogen synthase phosphatase is a heterotrimer. On ethanol treatment, the enzyme was dissociated to an active species with a molecular weight of 37,000 estimated by gel filtration. The yeast phosphatase dephosphorylated yeast glycogen synthase, rabbit muscle glycogen phosphorylase, casein, and the alpha subunit of rabbit muscle phosphorylase kinase, was not sensitive to heat-stable protein phosphatase inhibitor 2, and was inhibited 90% by 1 nM okadaic acid. Dephosphorylation of glycogen synthase, phosphorylase, and phosphorylase kinase by this yeast enzyme could be stimulated by histone H1 and polylysines. Divalent cations (Mg2+ and Ca2+) and chelators (EDTA and EGTA) had no effect on dephosphorylation of glycogen synthase or phosphorylase while Mn2+ stimulated enzyme activity by approximately 50%. The specific activity and kinetics for phosphorylase resembled those of mammalian phosphatase 2A. An antibody against a synthetic peptide corresponding to the carboxyl terminus of the catalytic subunit of rabbit skeletal muscle protein phosphatase 2A reacted with subunit C of purified yeast phosphatase on immunoblots, whereas the analogous peptide antibody against phosphatase 1 did not. These data show that this yeast glycogen synthase phosphatase has structural and catalytic similarity to protein phosphatase 2A found in mammalian tissues.

Chromatography, Affinity↗

PubMed1991

Cloning and expression of a yeast protein tyrosine phosphatase.

To study the regulation of tyrosine phosphorylation/dephosphorylation in Saccharomyces cerevisiae, a protein tyrosine phosphatase (PTPase) was cloned by the polymerase chain reaction (PCR). Conserved amino acid sequences within the mammalian PTPases were used to design primers which generated a yeast PCR fragment. The sequence of the PCR fragment encoded a protein with homology to the mammalian PTPases. The PCR fragment was used to identify the yeast PTP1 gene which has an open reading frame encoding a 335-amino acid residue protein. This yeast PTPase shows 26% sequence identity to the rat PTPase, although highly conserved residues within the mammalian enzymes are invariant in the yeast protein. The yeast PTP1 is physicallt linked to the 5'-end of a heat shock gene SSB1. This yeast PTP1 gene was expressed in Escherichia coli and obtained in a highly purified form by a single affinity chromatography step. The recombinant yeast PTPase hydrolyzed phosphotyrosine containing substrates approximately 1000 times faster than a phosphoserine containing substrate. Gene disruption of yeast PTP1 has no visible effect on vegetative growth.

Amino Acid Sequence↗

PubMed1991

A 48-kDa, S-antigen-like phosphoprotein in yeast DNA-replicative complex preparations.

A 48-kDa protein from the budding yeast Saccharomyces cerevisiae is antigenically and structurally similar to S-antigen from retina. Eight anti-S-antigen monoclonal antibodies, directed against distinct epitopes, cross-reacted with a yeast 48-kDa protein. Structural similarity between the bovine and yeast proteins was further demonstrated by comparison of tryptic peptide fragments containing one of these epitopes. This 48-kDa yeast protein appears to be a component of the replicative complex of the cell. It was found associated with immunoaffinity-purified yeast DNA polymerase I-primase and with yeast DNA-replicative complex. The 48-kDa protein was phosphorylated by a protein kinase activity endogenous to the replicative complex preparation. This phosphorylation was dependent on the cell division cycle gene CDC7. In addition, authentic bovine S-antigen, when added to yeast DNA polymerase I-primase, stimulated polymerase activity. These findings suggest that the yeast S-antigen-like protein may play a role in replication, and they raise the possibility that it may be involved in traversal of the G1/S boundary of the cell cycle.

Animals↗

PubMed1991

Expression and characterization of a recombinant yeast isoleucyl-tRNA synthetase.

We describe the heterologous expression of a recombinant Saccharomyces cerevisiae isoleucyl-tRNA synthetase (IRS) gene in Escherichia coli, as well as the purification and characterization of the recombinant gene product. High level expression of the yeast isoleucyl-tRNA synthetase gene was facilitated by site-specific mutagenesis. The putative ribosome-binding site of the yeast IRS gene was made to be the consensus of many highly expressed genes of E. coli. Mutagenesis simultaneously created a unique BclI restriction site such that the gene coding region could be conveniently subcloned as a "cassette." The variant gene was cloned into the expression vector pKK223-3 (Brosius, J., and Holy, A. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 6929-6933) thereby creating the plasmid pKR4 in which yeast IRS expression is under the control of the isopropyl-thio-beta-galactopyranoside (IPTG)-inducible tac promoter. Recombinant yeast IRS, on the order of 10 mg/liter of cell culture, was purified from pKR4-infected and IPTG-induced E. coli strain TG2. Yeast IRS was purified to homogeneity by a combination of anion-exchange and hydroxyapatite gel chromatography. Inhibition of yeast IRS activity by the antibiotic pseudomonic acid A was tested. The yeast IRS enzyme was found to be 10(4) times less sensitive to inhibition by pseudomonic acid A (Ki = 1.5 x 10(-5) M) than the E. coli enzyme. E. coli strain TG2 infected with pKR4, and induced with IPTG, had a plating efficiency of 100% at inhibitor concentrations in excess of 25 micrograms/ml. At the same concentration of pseudomonic acid A, E. coli strain TG2 infected with pKK223-3 had a plating efficiency less than 1%. The ability of yeast IRS to rescue E. coli from pseudomonic acid A suggests that the eukaryotic synthetase has full activity in its prokaryotic host and has specificity for E. coli tRNA(ile).

Base Sequence↗

PubMed1988

[Hybridization of homothallic wine yeasts with heterothallic strains].

Most of the yeast strains of industrial interest are homothallic, which makes genetic analysis as well as improvement of their desirable properties extremely difficult. In this work, all the wine yeasts analyzed, except for two "flor" yeasts which were able to generate heterothallic meiotic products, were homozygous for the HO allele of homothallism. The genetic analysis of one of the "flor" yeast spores, which was heterothallic, indicated that the strain carried an HO allele of homothallism and that its heterothallic behaviour was due to a genetic constitution HML MAT HMR HO. This HO allele of the "flor" yeast behaved differently from other HO alleles present in the wine yeasts. It gave rise to a very retarded homothallism, with formation of selfzygotes which presented an abnormal morphology. These zygotes generated selfdiploids whose ability to sporulate was very inefficient. The lag in the expression of the homothallism allowed the isolation of hybrids between meiotic products of the "flor" yeasts and heterothallic laboratory strains with a frequency of 10(-1), as compared to that of the meiotic products of other wine yeasts, which was of 10(-4) to 10(-6). This result indicates that, among other factors which could influence the frequency of hybrid formation, the lag in the expression of homothallism could be the most important one. The use of heterothallic laboratory strains of mating type as opposed to a strain of alpha mating type, as well as the frequency of viable nucleus in the hybrid zygote after conjugation, also seemed to influence the success of hybrid formation between laboratory strains and the wine homothallic strains used.

Genes, Fungal↗

PubMed1988

Myristoyl CoA:protein N-myristoyltransferase activities from rat liver and yeast possess overlapping yet distinct peptide substrate specificities.

A variety of eukaryotic viral and cellular proteins possesses an NH2-terminal N-myristoylglycine residue important for their biological functions. Recent studies of the primary structural requirements for peptide substrates of the enzyme responsible for this modification in yeast demonstrated that residues 1, 2, and 5 play a critical role in enzyme: ligand interactions (Towler, D. A., Adams, S. P., Eubanks, S. R., Towery, D. S., Jackson-Machelski, E., Glaser, L., and Gordon J. I. (1987b) Proc. Natl. Acad. Sci. U. S. A. 84, 2708-2812). This was determined by examining as substrates a series of synthetic peptides whose sequences were systematically altered from a "parental" peptide derived from the known N-myristoylprotein bovine heart cyclic AMP-dependent protein kinase (A kinase) catalytic subunit. We have now extended these studies in order to examine structure/activity relationships in the COOH-terminal regions of octapeptide substrates of yeast N-myristoyltransferase (NMT). The interaction between yeast NMT and the side chain of residue 5 in peptide ligands is apparently sterically constrained, since Thr5 is unable to promote the very high affinity binding observed with a Ser5 substitution. A substrate hexapeptide core has been defined which contains much of the information necessary for recognition by this lower eukaryotic NMT. Addition of COOH-terminal basic residues to this hexapeptide enhances peptide binding, while COOH-terminal acidic residues destabilize NMT: ligand interactions. Based on the results obtained from our in vitro studies of over 80 synthetic peptides and yeast NMT, we have identified a number of potential N-myristoylproteins from searches of available protein databases. These include hepatitis B virus pre-S1, human SYN-kinase, rodent Gi alpha, and bovine transducin-alpha. Peptides corresponding to the NH2-terminal sequences of these proteins and several known N-myristoylproteins were assayed using yeast NMT as well as partially purified rat liver NMT. While a number of the synthetic peptides exhibited similar catalytic properties with the yeast and mammalian enzymes, surprisingly, the SYN-kinase, Gi alpha, and transducin-alpha peptides were N-myristoylated by rat NMT but not by yeast NMT. This suggests that either multiple NMT activities exist in rat liver or the yeast and rodent enzymes have similar but distinct peptide substrate specificities.

Acyl Coenzyme A↗

PubMed1985

[Recombinant plasmids carrying multiple markers: isolation during yeast co-transformation].

Cotransformants of yeast cells by two partially homologous plasmids, one of which is incapable of autonomous replication, has been used to construct multiply marked recombinant plasmids. Only simultaneous elimination of three yeast markers was registered when episomal plasmid, carrying Ade2 gene, and integrative plasmid, carrying yeast genes LEU2 and URA3, were cotransformed. Transformants, in which yeast genes LEU2, URA3 and HIS3 are linked, have been isolated by analogous technique. The genetic analysis has confirmed existence of plasmid cointegrates in the transformant cells, which carry three yeast genes, bacterial DNA fragment and 2 micrometers DNA fragment, coding for replicative functions. Recombination in the region of bacterial plasmid pBR322 might have resulted in formation of such plasmids. Plasmid recombination in cotransformants has been used to construct multiply marked circular chromosomes, having included yeast genes LEU2, URA3 and TRP1, centromere of the IV yeast chromosome and the sequence coding for their replication in yeast as well as in E. coli cells.

Genetic Markers↗

PubMed1985

Intracellular and extracellular defenses of human phagocytes against Blastomyces dermatitidis conidia and yeasts.

The lesions of blastomycosis are characterized by both suppuration and granuloma formation, but the relative roles of human neutrophils, monocytes, and macrophages against Blastomyces dermatitidis are poorly defined. Our studies reveal that B. dermatitidis yeasts are generally too large to be ingested by polymorphonuclear neutrophils (PMNs), and are killed predominantly by external PMN attachment and degranulation, whereas conidia are first ingested, then killed. PMN function is maximal in the presence of serum, divalent cations, and complement, and killing is more efficient for conidia (approximately 50%) than for yeasts (approximately 20%). PMNs that have degranulated, but remain attached to yeasts, block access by contiguous PMNs. When degranulated PMNs are removed, allowing access by fresh PMNs, there is a further increment in yeast killing. Both conidia and yeasts are killed by predominantly oxidative PMN mechanisms, with conidia being greater activators of the respiratory burst, and proportionately more influenced by oxidative inhibitors. Peripheral blood monocytes can kill conidia (approximately 35%), but are feebly active against yeasts (approximately 5%). Monocyte-derived macrophages kill approximately 90% of conidia and 40% of yeasts. The dramatic susceptibility of conidia, the infective particles of B. dermatitidis, to nonspecific phagocytic host defenses may help to explain the relative rarity of blastomycosis as a clinical problem. The presence of PMNs in lesions of blastomycosis may indicate an active, although limited, role of these cells in host defense against B. dermatitidis yeasts.

Blastomyces↗

PubMed1984

Synergistic interaction of baker's yeast and iron in the enhancement of bacterial virulence.

The virulence-enhancing interaction of baker's yeast and different iron preparations (ferric ammonium citrate and iron dextran) was tested in mice challenged with Salmonella typhi and Vibrio cholerae (Inaba and Ogawa) strains. The virulence-enhancing effect of the yeast + iron combination increased significantly as compared to that of either yeast or iron alone. Toxicity assays of the single and combined baker's yeast and iron preparations by the mouse weight gain test have shown that the combinations are considerably more toxic than either single agent, probably owing to the presence of yeast. Examination of the single and combined preparations for influence on body temperature of mice has revealed a general hypothermic action, which was strongest in the combinations, owing again to the yeast. Theoretical considerations on the underlying mechanism of the virulence-enhancing effect have supported the hypothesis that the effect might be associated with the strong hypothermic action produced by baker's yeast and baker's yeast + iron combinations, in as much as hypothermia increases the production of siderophores which ensure the acquisition of iron indispensable for bacterial growth.

Animals↗

PubMedDate not supplied

[Effect of the cultivation temperature on the growth and chemical composition of the methanol-assimilating yeast Candida boidinii].

The yeast Candida boidinii T2A was cultivated in a medium containing methanol or glucose as a sole carbon and energy source, and the effect of the cultivation temperature on the specific growth rate, the economic coefficient and the chemical composition of the yeast was studied in a continuous chemostat process. The specific rates of the yeast growth increase with the cultivation temperature up to optimal limits and then lower down abruptly in the supraoptimal zone. The maximal specific rate of the yeast growth in a medium with methanol at 30 degrees C is 0.24 h-1, while in a medium with glucose a 32 degrees C, it equals 0.38 h-1. In the suboptimal zone, the economic coefficient of the yeast growing in a medium with methanol at a dilution rate above 0.06 h-1 remains, for all practical purposes, at the same level (38-41%), while supraoptimal temperatures decrease the economic coefficient of the yeast. The results show a change in the content of protein and RNA as a function of the cultivation temperature and the dilution rate. It is concluded that the macromolecular composition of the yeast biomass is determined not only be the dilution rate, but also depends of temperature which regulates the rate of the yeast growth.

Candida↗

PubMed1996

Pharmacological characterization of the rat A2a adenosine receptor functionally coupled to the yeast pheromone response pathway.

The rat A2a adenosine receptor, a G protein-coupled receptor, was functionally expressed in the yeast Saccharomyces cerevisiae. High affinity binding sites for A2a adenosine agonists were detected in yeast membranes containing the endogenous Grx protein Gpa1. Agonist saturation binding isotherms using [3H]5'-N-ethylcarboxamidoadenosine indicated that the A2a adenosine receptor expressed in yeast cell membranes displays pharmacological properties equivalent to those observed when the receptor is expressed in human embryonic kidney 293 cell membranes. The rank order of potency of various agonists in [3H]5'-N-ethylcarboxamidoadenosine competition binding assays performed with yeast cell membranes was comparable to that seen for the receptor expressed in mammalian cell membranes. Adenosine agonist-dependent growth response of yeast strains expressing the A2a adenosine receptor was elicited via activation of the yeast pheromone-response pathway. Induction of a pheromone-responsive FUS1-HIS3 reporter gene in far1 his3 cells permits cell growth in medium lacking histidine. The sensitivity of the bioassay was increased by deletion of the STE2 gene, which encodes the yeast alpha-mating pheromone receptor. The growth response was dose dependent, and agonists of varying affinities displayed a rank order of potency comparable to that observed in competition binding assays. Agonist-activated growth assays performed in liquid culture gave ED50 values for various adenosine agonists consistent with reported Kd alpha values. Yeast strains expressing a single receptor/G protein complex will be useful as a model system for the study of receptor/G protein interactions in vivo.

Adenosine↗

PubMed1997

2-Deoxy-D-glucose induced modulation of DNA damage repair, survival, mutagenesis and recombinogenesis in 8-MOP+UVA treated yeast.

Cellular and genomic effects of post-treatment repair modulation by 2-deoxy-D-glucose (2-DG) and yeast extract were studied in 8-MOP + UVA treated cells of Saccharomyces cerevisiae. The type of lesions and their repair in phosphate buffer glucose (PBG) differed with UVA dose. At low UVA dose (1.4 kJ/m2), lesions were sublethal and mutagenic and did not repair by recombinogensis. The fraction of potentially lethal lesions and lesions repaired by recombinogenesis increased with UVA dose. Cellular repair in PBG was largely error-free and was inhibited by 2-DG. Yeast extract enhanced cellular repair and also recombinogensis; 2-DG in presence of yeast extract promoted error-prone repair. Pulsed-field gel electrophoresed chromosomal DNA bands did not show observable alterations immediately after 8-MOP + UVA treatment. On post-treatment incubation in PBG, the intensity ratio (rho n), of each band altered in a biphasic manner showing decrease first, followed by either increase or no change upto 24 hr depending upon UVA exposure dose. Presence of 2-DG in PBG inhibited decrease in rho n in a concentration dependent manner. Yeast extract reduced the time of first phase of DNA repair. 2-DG and yeast extract together reduced the time of first phase of repair and also inhibited the subsequent increase in rho n, which was observed in the case of yeast extract in PBG. It is proposed that (i) 2-DG in PBG inhibits excision of DNA damage and error-free repair; (ii) yeast extract stimulates the error-prone repair associated with cell cycle and recombinogenesis; (iii) 2-DG in presence of yeast extract allows excision of damage but inhibits build up through recombinogenesis inducing instead, cell cycle associated error-prone repair. A simple schematic model has been proposed to explain these events.

DNA Damage↗

PubMed2025

The Southern Hemisphere yeast frontier: from nature dwellers to accomplished fermenters.

Yeast biodiversity has been extensively investigated by wealthy countries of the Northern Hemisphere. In contrast, despite the widespread use of fermentation practices in the Southern Hemisphere, yeast diversity in this region remains largely underexplored. However, this trend is beginning to shift as several reports have started to document yeast populations both in the natural environment and in association with the fermentation of various substrates, including grape and apple juice, cocoa and coffee beans, grains, fruits, or tree sap. Numerous yeast species from the Southern Hemisphere have now been described and characterized, with whole-genome sequencing providing essential insights into the evolutionary history of wild yeast isolates from this region. This review highlights the emerging research on yeast biodiversity in the Southern Hemisphere and explores the application of diverse yeast species in the food and beverage industries.

Fermentation↗

PubMed1997

Predacious yeasts.

Haustorium-mediated predation was observed in seven yeast species. Arthroascus javanensis, Botryoascus synnaedendrus, Guilliermondella selenospora, Saccharomycopsis fibuligera, and three hitherto unknown species penetrate and kill other yeasts. These yeasts share an unusual requirement for organic sulphur. One isolate recovered from Australian Hibiscus was studied in detail and found to attack a broad range of prey species, including ascomycetous and basidiomycetous yeasts as well as moulds. Predation was most effective when growth was on a solid surface and the medium was poor in complex nutrients. Organic sulphur (exemplified by methionine) was identified as a key factor. It serves as a nutritional benefit to the predator and, depending on the concentration, acts as either an inhibitor of predation or possibly a signal for detection of prey. Sampling of a yeast habitat with a medium selective for selenium-resistant yeasts indicated that auxotrophic and predacious yeasts might be more widespread than anticipated.

Antibiosis↗