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PubMed1994

Yeast as a model system for mammalian seven-transmembrane segment receptors.

Investigators have used the budding yeast Saccharomyces cerevisiae as a model system in which to study the beta-adrenergic receptor, the T-cell receptor pathway, initiation of mammalian DNA replication, initiation of mammalian transcription, secretion, the CDC2 kinase system, cell cycle control, and aging, as well as the function of oncogenes. This list continues to grow with the discovery of an immunoglobulin heavy-chain binding homologue in yeast, an Rb binding protein homologue, and a possible yeast arrestin. Yeast is relatively easy to maintain, to grow, and to genetically manipulate. A single gene can be overexpressed, selectively mutated or deleted from its chromosomal location. In this way, the in vivo function of a gene can be studied. It has become reasonable to consider yeast as a model system for studying the seven transmembrane segments (7-TMS) receptor family. Currently, subtypes of the beta-adrenergic receptor are being studied in yeast. The receptor and its G alpha-G-protein, trigger the mating pheromone receptor pathway. This provides a powerful assay for determining receptor function. Studies expressing the muscarinic cholinergic receptor in yeast are underway. The yeast pheromone receptor belongs to this receptor family, sharing sequence and secondary structure homology. An effective strategy has been to identify a yeast pathway or process which is homologous to a mammalian system. The pathway is delineated in yeast, identifying other genetic components. Then yeast genes are used to screen for human homologues of these components. The putative human homologues are then expressed in yeast and in mammalian cells to determine function. When this type of "mixing and matching" works, yeast genetics can be a powerful tool.

Antigens↗
PubMed2003

Yeast interactions and wine flavour.

Wine is the product of complex interactions between fungi, yeasts and bacteria that commence in the vineyard and continue throughout the fermentation process until packaging. Although grape cultivar and cultivation provide the foundations of wine flavour, microorganisms, especially yeasts, impact on the subtlety and individuality of the flavour response. Consequently, it is important to identify and understand the ecological interactions that occur between the different microbial groups, species and strains. These interactions encompass yeast-yeast, yeast-filamentous fungi and yeast-bacteria responses. The surface of healthy grapes has a predominance of Aureobasidium pullulans, Metschnikowia, Hanseniaspora (Kloeckera), Cryptococcus and Rhodotorula species depending on stage of maturity. This microflora moderates the growth of spoilage and mycotoxigenic fungi on grapes, the species and strains of yeasts that contribute to alcoholic fermentation, and the bacteria that contribute to malolactic fermentation. Damaged grapes have increased populations of lactic and acetic acid bacteria that impact on yeasts during alcoholic fermentation. Alcoholic fermentation is characterised by the successional growth of various yeast species and strains, where yeast-yeast interactions determine the ecology. Through yeast-bacterial interactions, this ecology can determine progression of the malolactic fermentation, and potential growth of spoilage bacteria in the final product. The mechanisms by which one species/strain impacts on another in grape-wine ecosystems include: production of lytic enzymes, ethanol, sulphur dioxide and killer toxin/bacteriocin like peptides; nutrient depletion including removal of oxygen, and production of carbon dioxide; and release of cell autolytic components. Cell-cell communication through quorum sensing molecules needs investigation.

Bacteria↗
PubMed2003

Molecular characterization of carotenogenic yeasts from aquatic environments in Patagonia, Argentina.

Fifteen aquatic environments (lakes, lagoons and rivers) of glacial origin in the northern Andean Patagonia (Argentina) were surveyed for the occurrence of red yeasts. Subsurface water samples were filtered and used for colony counting and yeast isolation. A preliminary quantitative analysis indicated that total yeast counts ranged between 0 and 250 cells l(-1). A polyphasic approach including physiological and molecular methods was used for the identification of 64 carotenogenic yeast strains. The molecular characterisation of the isolates was based on the mini/microsatellite-primed PCR technique (MSP-PCR) employing the (GTG)5 and the M13 primers. Comparison of representative fingerprints of each group with those of the type strains of pigmented yeasts allowed the expeditious identification of 87.5% isolates. The sequence analysis of the D1/D2 domains of the 26S rDNA was employed to confirm identifications and in the characterization of the unidentified MSP-PCR groups. Teleomorphic yeast species were detected by performing sexual compatibility assays. The isolates corresponded to 6 genera and 15 yeast species, including four new yeast species of the genera Cryptococcus (1), Rhodotorula (1) and Sporobolomyces (2). Rhodotorula mucilaginosa was found in the majority of the samples and represented ca. 50% of the total number of isolates. However, this yeast was not detected in aquatic environments with very low anthropic influence. Other frequent yeast isolates were teleomorphic yeast species of Rhodosporidium babjevae, R. kratochvilovae and Sporidiobolus salmonicolor. This study represents the first report on red yeast occurrence and biodiversity in northwestern Patagonia.

Argentina↗
PubMed1983

Transcription initiation in eukaryotes: analysis of heterologous in vitro systems utilizing components from mammalian and yeast cells.

The properties of heterologous in vitro transcription systems utilizing components from mammalian and yeast cells have been investigated. Purified yeast RNA polymerase II, when supplemented with a full complement of mammalian transcription factors, does not promote specific transcription initiation on cloned mammalian class II genes. Similarly, a complete mammalian transcription system does not initiate specific transcription on cloned yeast class II genes. These results indicate evolutionary divergence in function of yeast and mammalian class II genes and the associated transcription apparatus. The functional differences observed in this study are corroborated by previously reported structural differences between yeast and mammalian RNA polymerase II and class II genes. In contrast, the mechanism of eukaryotic class III gene transcription appears to be evolutionarily conserved. Thus, a mammalian transcription extract specifically transcribes the cloned yeast 5S rRNA gene. This system synthesizes without processing the 130 base 5S rRNA precursor, and this primary transcript may be processed to the mature 120 base RNA using a partially purified yeast processing activity. An homologous yeast class III transcription system has also been developed. This yeast system contains all components necessary for proper synthesis, processing and splicing of yeast tRNA precursors. Using the homologous yeast transcription system, a template in which the 5' flanking region and first 5 base pairs of the 5S rRNA gene had been deleted is utilized to synthesize a 120 base transcript, but the efficiency of transcription is reduced to about 10% that of the wild type gene. Thus, the yeast 5S rRNA gene has an internal transcription control region, but the immediate 5' flanking sequence have effects on the level of transcription.

Animals↗
PubMed1994

Effects of brewer's yeast on glucose tolerance and serum lipids in Chinese adults.

This study was designed to investigate the supplemental effects of brewer's yeast on serum glucose and lipids in Chinese adults. Twenty-two participants (8 males and 14 females) were recruited from Pingtung city. Mean age of the group was 51 yr, and fasting values of total cholesterol and glucose were from 3.21 to 6.90 and 4.3 to 6.2 mmol/L, respectively. Before supplementation, a 75 g oral glucose load was administered after an overnight (9 h) fast. Blood was drawn before and at 30, 60, 90, and 120 min after the glucose load. The subjects were randomly assigned into either brewer's yeast or torula yeast group and consumed 10 g yeast powder daily for 12 wk. Brewer's yeast demonstrated a beneficial effect on decreasing serum triacylglycerol values (p < 0.05). The brewer's yeast supplemented group had an increment at 0 min (p < 0.01) and significant decrements at 60 (p < 0.05) and 90 (p < 0.01) min of oral glucose tolerance test (OGTT). However, after 12-wk supplementation, torula yeast increased glucose values at both 0 and 30 min (p < 0.05) after a glucose load. Brewer's yeast and torula yeast addition significantly altered glucose concentrations at 60 min after the glucose dosage (p < 0.05). Brewer's yeast had significantly decreasing effects on insulin output both at 90 (p < 0.05) and 120 min (p < 0.01) after the glucose load. Likewise, serum insulin contents decreased at 90 min (p < 0.01) after supplementation in the group given torula yeast. Brewer's yeast supplementation had beneficial effects both on serum triacylglycerol and on 60-min and 90-min glucose values of OGTT.

Adult↗
PubMed1992

A new and simple method for studying the binding and ingestion steps in the phagocytosis of yeasts.

Autoclaved yeasts are stained light pink by May-Grünwald Giemsa (MGG). If treated with tannic acid solution just before MGG staining, they display a deep violet color. It seemed possible that these properties could be used to discriminate between extra- and intracellular yeasts in a phagocytosis test, extracellular yeasts being violet and intracellular yeasts being pink. To validate this protocol, quantitative studies of phagocytosis by MALU cells (a murine macrophage cell line) were performed in the presence or absence of drugs known to interfere with phagocytosis. After treatment of cells with cytochalasin B, the mean number of pink yeasts per cell decreased in a dose-dependent manner, the mean number of violet yeasts increased in a dose-dependent manner, whereas the total number of cell-associated yeasts remained almost unchanged whatever the dose used. After treatment with alpha-mannans or chloroquine, the mean numbers of both violet and pink yeasts decreased in a dose-dependent manner. These results confirmed that (i) violet yeasts are extracellular, (ii) autoclaved yeasts recognize lectin receptors, and (iii) unstained (pink) yeasts are intracellular. We show that this simple method can be used for quantitative light microscopic analysis of both the attachment and internalization steps in the phagocytosis of yeasts.

Animals↗
PubMed2006

A heterologous system for assembly of retroviral gene vectors: intracellular budding in yeast?

Mammalian retroviral gene vectors are of particular importance in gene therapy because of their efficient chromosomal integration and resulting stable maintenance of transgenes. These vectors are currently produced in mammalian cells, with low yield and at substantial expense. Therefore, a more efficient heterologous production system for retroviral vectors would be desirable. With their impressive track record in biotechnology, various yeast species appear like ideal organisms to generate retroviral vectors. Typically, retroviral vector particles emerge from mammalian cells after budding at the plasma membrane. However, in yeast, viral budding at the plasma membrane is blocked by the cell wall. At the same time, mass production of enveloped viral vectors in yeast protoplasts is technically challenging. Recent reports indicated the generation of infectious virions via intracellular budding for some combinations of retroviruses and mammalian cells. Relying on these data I hypothesise that a successful assembly of the retroviral transducing particles can be accomplished intracellularly inside yeast cells with a normal cell wall. Firstly, it is possible that some of the intracellular yeast compartments have all the necessary host factors that are required for successful RNA packaging, budding and maturation of infectious retroviral vector particles. Secondly, it might be possible to improve intracellular viral vector production by artificially targeting viral cores to bud at specific intracellular vesicular structures using appropriate targeting or retention signals. A suitable envelope protein, conferring infectivity and specific cellular tropism to the vector particles, can be expressed in yeast or, alternatively, 'bald' viral particles without envelope protein can be produced in yeast and later complexed with a desired envelope protein in vitro. Retroviral budding on yeast intracellular membranes can rely on the same host factors that are used by yeast retrotransposons driving intracellular formation of non-infectious virus-like particles. It is likely that optimal vector packaging system can be found as a result of the dedicated screening of the various retroviral vectors against an array of yeast species. The central implication of the hypothesis is that budding of retroviral vector particles inside yeast cells, with no need for obtaining and maintaining yeast spheroplasts or protoplasts, can be an efficient and economical method of mass production of these valuable gene therapy vectors.

Biotechnology↗
PubMed1996

Polymerization and in vitro motility properties of yeast actin: a comparison with rabbit skeletal alpha-actin.

Actin purified from the yeast (Saccharomyces cerevisae) was polymerized faster than rabbit skeletal alpha-actin by MgCl2. The two actins polymerized at similar rates in the presence of CaCl2. Yeast actin, up to 25 microM, was not polymerized by KCl (100-300 mM); the monovalent salt also inhibited the MgCl2-induced polymerization of actin. The local structure of the subdomain-2 region in yeast actin filaments was probed by subtilisin and trypsin digestions. Loop 38-52 appeared more flexible and accessible to subtilisin in yeast than in rabbit actin. In contrast, tryptic digestions at Lys-61 and -68 occurred at the same rate for yeast and alpha-actin filaments. Modification of yeast actin by a sulfhydryl reagent CPM [7-(diethylamino)-3-(4'-maleimidophenyl)-4-methylcoumain] was specific to the Cys-374 residue; no labeling of a yeast actin mutant containing an alanine substitution for cysteine 374 was observed. The rates of Cys-374 labeling by CPM were similar for yeast and muscle actin, suggesting a similar environment for the C terminus in both polymers. In the in vitro motility assays, yeast actin required higher concentrations of heavy meromyosin (HMM) for its sliding than did the rabbit actin. At saturating concentrations of HMM, the sliding velocities of both actins were the same (3.0 microns/s). Relative forces generated by HMM with yeast and muscle actin were assessed by monitoring their in vitro motility in the presence of NEM-HMM load. The sliding of yeast actin was stopped at a level of external load (molar ratio NEM-HMM/HMM = 0.25) lower than that of muscle actin (NEM-HMM/HMM = 0.43), suggesting lower force production with yeast actin. These results are discussed in terms of the myosin cross-bridge cycle and actomyosin interactions.

Actins↗
PubMedDate not supplied

Construction of a cultivation system of a yeast single cell in a cell chip microchamber.

A novel single cell screening system was constructed using a yeast cell chip in combination with the yeast cell surface engineering [NanoBiotechnology 2005, 1, 105-111]. Enzymes or functional proteins displayed on a yeast cell surface can be used as a protein cluster. To achieve high-throughput screening of protein libraries on the cell surface, a catalytic reaction by a single cell-surface-engineered yeast cell was successfully carried out in the microchamber on the yeast cell chip. After screening, to replicate a target cell for use in measuring of activity, DNA sequencing, and preservation, a novel single cell cultivation system in the yeast cell chip was constructed. To avoid damage of the rapid dry up of medium in the microchamber array, the yeast cell chip was modified with a protection sheet, so that the modified chip was like a micro-culture tank constructed on the yeast cell chip microchamber. As a result, single yeast cell cultivation in the yeast cell chip microchamber was observed, and the modified yeast cell chip was evaluated to be good for a single cell selection. The improvement showed that the single cell screening system coupled with the single cell cultivation using the modified yeast cell chip may be superior to that by a cell sorter for the isolation of a target cell and its practical use.

Cell Count↗
PubMed1979

High-frequency transformation of yeast: autonomous replication of hybrid DNA molecules.

A set of vector DNAs (Y vectors) useful for the cloning of DNA fragments in Saccharomyces cerevisiae (yeast) and in Escherichia coli are characterized. With these vectors, three modes of yeast transformation are defined. (i) Vectors containing yeast chromosomal DNA sequences (YIp1, YIp5) transform yeast cells at low frequency (1--10 colonies per microgram) and integrate into the genome by homologous recombination; this recombination is reversible. (ii) Hybrids containing endogenous yeast plasmid DNA sequences (YEp2, YEp6) transform yeast cells at much higher frequency (5000--20,000 colonies per microgram). Such molecules replicate autonomously with an average copy number of 5--10 covalently closed circles per yeast cell and also replicate as a chromosomally integrated structure. This DNA may be physically isolated in intact form from either yeast or E. coli and used to transform either organism at high frequency. (iii) Vectors containing a 1.4-kilobase yeast DNA fragment that includes the centromere linked trp1 gene (YRp7) transform yeast with an efficiency of 500--5000 colonies per microgram; such molecules behave as minichromosomes because they replicate autonomously but do not integrate into the genome. The uses of Y vectors for the following genetic manipulations in yeast are discussed: isolation of genes; construction of haploid strains that are merodiploid for a particular DNA sequence; and directed alterations of the yeast genome. General methods for the selection and the analysis of these events are presented.

DNA Replication↗
PubMed2005

Detection of Helicobacter pylori-specific genes in the oral yeast.

BACKGROUND: Until today, human stomach is the only recognized habitat of Helicobacter pylori. However, recruitment of DNA-based methods has made possible the detection of H. pylori in water and oral cavity, thus suggesting fecal-oral and oral-oral routes for transmission of H. pylori, respectively. In this study, yeast has been proposed as a common vector for transmission of H. pylori. Thus designed primers were recruited to target 16S rDNA and cagA genes in the oral yeasts by PCR. MATERIALS AND METHODS: Eighteen yeasts were examined microscopically for the presence of bacterial-like bodies. DNAs were extracted from oral yeasts using phenol-chloroform method. Amplification conditions were optimized as 33 cycles and annealing temperatures of 63 degrees C for 16S rDNA and 51 degrees C and 52 degrees C for cagA gene which was targeted in two steps. DNAs of H. pylori and Saccharomyces cerevisiae were used as controls. Polymerase chain reaction (PCR) products of two genes from one yeast and from H. pylori were cloned in pCAP and subsequently subcloned in pSK+ and were sequenced. RESULTS: Bacterial-like bodies were observed in all oral yeasts. The amplified products of 16S rDNA from all oral yeasts were homologous in size with those of H. pylori. Fifteen out of eighteen (83%) yeasts contained cagA gene, homologous to H. pylori. CagA was not amplified from three yeasts and S. cerevisiae. Analysis of the sequenced products of 16S rDNA and cagA from one oral yeast showed 98% homology with those of H. pylori. CONCLUSIONS: The presence of H. pylori inside the yeast was indicated by light microscopy and PCR. It appears that yeasts, which are abundant in nature and thrive the mucosal surfaces of human, might serve as reservoirs and vehicles of H. pylori.

Antigens, Bacterial↗
PubMed1998

Risk factors for colonization with yeast species in a Veterans Affairs long-term care facility.

OBJECTIVES: To assess colonization and serious infection with yeasts and the risk factors that are associated with colonization by these organisms. DESIGN: Monthly surveillance for colonization and infection over a period of 2 years. SETTING: A long-term-care facility (LTCF) attached to an acute-care Veterans Affairs Medical Center. PARTICIPANTS: The 543 men and 10 women in the facility. MEASUREMENTS: Colonization and serious infection rates with yeasts. Analysis of risk factors associated with yeast colonization of residents. RESULTS: Colonization rates were relatively stable during the 2-year period (53+/-1.8% patients colonized per month). Candida albicans was the most common colonizer, found in 35+/-.9% of patients colonized per month. The pharynx was the most commonly colonized site, with 41+/-1.4% of patients per month with pharyngeal colonization. Eighty-four percent of patients remaining in the facility for 3 or more months were colonized by yeast at some time during their stay. Presence of neurogenic bladder, leg amputation, or a low serum albumin were independently associated with yeast colonization; neither diabetes mellitus nor functional status was a risk factor for colonization by yeasts. Only four serious yeast infections in four patients (esophagitis and three urinary tract infections) were found during the 2-year period; all infections occurred in patients who were colonized by yeasts previously. CONCLUSION: In our LTCF, colonization of patients by yeasts occurred commonly in those residents remaining in the facility for 3 or more months. However, serious yeast infections occurred infrequently. It is likely that colonization of residents of LTCFs by yeasts may only become clinically important when the patient is transferred to an acute-care hospital where additional risk factors may allow the development of serious yeast infection.

Aged↗
PubMed1975

Genital yeasts in female patients attending a VD clinic.

A study of 552 female patients was undertaken to determine the frequency of yeast infections in women attending a V.D. clinic. The findings were as follows: (1) 207 of the 552 (37.5 per cent.) were found to have yeasts. (2) C. albicans accounted for 86 per cent. of these yeasts. (3) There was no difference in incidence related to age or seasonal variation. (4) Oral contraceptives increased the incidence of yeasts (43.2 per cent. on "the pill"; 33.2 per cent. not on the pill"), but the incidence of Trichomonas was decreased (6.8 per cent. on "the pill", 19.3 per cent. not on "the pill"). (5) Previous antibiotics also contributed to the incidence; 23.2 per cent. of patients with yeasts had had antibiotics previously compared with 13.6 per cent. of those without yeasts. (6) Other infections were associated in seventy cases (33.8 per cent.). (7) Culture is essential for the detection of yeasts; 64 per cent. were positive only on culture. (8) Symptoms were present in 70 per cent. of patients with yeasts. (9) 93 male consorts were seen and in 31 (33 per cent.) yeasts were detected by smear, or culture. Of the 47 in whom cultures were examined, 23 (49 per cent.) were positive. The general factors affecting the incidence of yeasts are discussed as well as the differentiation of the saprophytic from the pathogenic role of yeasts. It is suggested that asymptomatic yeast infections are often best treated, but that each case should be considered individually. Male consorts should also be treated to prevent re-infection.

Adolescent↗
PubMed2006

Simple improvement in freeze-tolerance of bakers' yeast with poly-gamma-glutamate.

We examined the effect of poly-gamma-glutamate (PGA) on the freeze-tolerance of four types of commercial bakers' yeast (freeze-tolerant, osmotic-tolerant, low-temperature-sensitive, and ordinary bakers' yeasts). The survival ratio of ordinary bakers' yeast cells frozen at -30 degrees C for 3 d in a medium (0.5% yeast extract, 0.5% peptone, and 2% glucose: YPD medium) was improved by adding more than 1% PGA to the medium; the survival ratio increased from about 10% to more than 70%. All PGA preparations, which differed in average molecular mass (50, 2,000, 4,000, 6,000, 8,000, and 10,000 kDa), showed a similar cryoprotecive effect on the cells. Similar results were also obtained with other types of bakers' yeast, sake yeast and beer yeast. When the four types of bakers' yeast cell were frozen at -30 degrees C for 3 d in dough supplemented with more than 1% PGA, the cells (after freezing and thawing) showed higher leavening ability than those frozen in dough without PGA, irrespective of the molecular mass of PGA. Thus, PGA appears to protect bakers' yeast from lethal freeze injury, leading to a high leavening ability after freezing and thawing. PGA did not decrease the original leavening ability of the bakers' yeast, and was not decomposed by the yeast cells. PGA suppressed the decrease in leavening ability during a prolonged fermentation time, probably because PGA adsorbed inhibitory metabolites accumulated in the dough. PGA could prove useful for improving the freeze-tolerance of bakers' yeast by its addition to dough.

Cold Temperature↗
PubMed2000

Efficacy of yeast phytase in improving phosphorus bioavailability in a corn-soybean meal-based diet for growing pigs.

Crossbred barrows (n = 66; 6 wk old) were used in a 6-wk experiment to evaluate the efficacy of phytase from yeast or Aspergillus niger on performance, tibial characteristics, and serum inorganic P concentration. We also investigated the stability of these phytases in acidic solutions with pepsin, which simulated gastric conditions. Pigs were fed a P-adequate diet containing .34% nonphytate-P or a low-P diet containing .20% nonphytate-P. The low-P diet was supplemented with 0, 1,000, 2,000, or 4,000 phytase units (PU; the activity at optimal pH, i.e., pH 4.2 for yeast phytase and pH 5.5 for phytase from Aspergillus niger)/kg of yeast phytase, or 1,000 PU/kg phytase from Aspergillus niger. The graded level of yeast phytase linearly increased ADG (P = .047), tibial weight (P = .091), tibial density (P < .001), and P concentration in tibial cortex (P = .018). Aspergillus niger phytase also increased ADG (P = .022), serum inorganic P concentration (P < .001), tibial density (P = .007), and tibial P concentration (P = .025). The pigs given 1,000 PU/kg Aspergillus niger phytase showed greater ADG (P = .091), tibial density (P= .001), and tibial P concentration (P = .062) than those given 1,000 PU/kg yeast phytase. No measurements differed (P > .31) between the pigs given 1,000 PU/kg Aspergillus niger phytase and those given 4,000 PU/kg yeast phytase. These results suggested that yeast phytase improves bioavailability of P in the diet for growing pigs but the efficacy of yeast phytase is less than that of Aspergillus niger phytase. During incubation in acidic solutions with pepsin, yeast phytase (P < .001) lost more of its activity than Aspergillus niger phytase. This lesser stability of yeast phytase may be responsible for the poorer efficacy of yeast phytase than that of Aspergillus niger. In summary, supplementation of swine diets with yeast phytase is beneficial, but its efficacy is less than that of Aspergillus niger phytase.

6-Phytase↗
PubMed2003

Growth performance, nutrient digestibility, and fecal microflora in weanling pigs fed live yeast.

Two experiments were conducted to evaluate the effects of live yeast supplementation on nursery pig performance, nutrient digestibility, and fecal microflora and to determine whether live yeast could replace antibiotics and growth-promoting concentrations of Zn and Cu in nursery pigs. In Exp. 1, 156 pigs were weaned at 17 d of age (BW = 5.9 kg) and allotted to a 2 x 2 factorial randomized complete block design (six or seven pigs per pen with six pens per treatment). Factors consisted of 1) dietary supplementation with oat products (oat flour and steam-rolled oats; 0 or 27.7%) and 2) yeast supplementation at 0 or 1.6 x 10(7) cfu of Saccharomyces cerevisiae SC47/g of feed. In Exp. 2, 96 pigs were weaned at 17 d of age and allotted to a 2 x 2 factorial randomized complete block design (four pigs per pen with six pens per treatment) with factors of 1) diet type (positive control containing growth-promoting concentrations of Zn, Cu, and antibiotics or negative control) and 2) live yeast supplementation (0 or 2.4 x 10(7) cfu of Saccharomyces cerevisiae SC47/g of feed). The inclusion of oat products in Exp. 1 decreased (P < 0.10) overall ADG and final BW. Yeast supplementation did not affect growth performance of pigs in Exp. 1 (P = 0.65); however, ADG in Exp. 2 was 10.6% greater (P < 0.01) and ADFI was increased by 9.4% (P < 0.10) in pigs supplemented with yeast in the positive control diet. Addition of Zn, Cu, and antibiotics to the diet improved gain:feed ratio during the prestarter period (P < 0.02) and overall (P = 0.10). In Exp. 1, inclusion of oat products increased (P < 0.01) total bacteria in feces when measured on d 10. Fecal lactobacilli measured on d 28 were reduced (P < 0.05) in pigs fed diets with oat products and yeast (interaction, P < 0.05). In Exp. 2, yeast supplementation decreased (P < 0.05) total bacteria and lactobacilli. Dietary yeast resulted in a greater (P < 0.05) yeast count in feces of pigs during the starter phase of Exp. 1. Yeast decreased (P < 0.10) the digestibility of DM, fat, and GE in the prestarter phase and DM, fat, P, and GE in the starter phase, whereas oat products increased the digestibility of DM, CP, fat, and GE (P < 0.05) in the prestarter phase. Results indicate that live yeast supplementation had a positive effect on nursery pig performance when diets contained growth-promoting antimicrobials. Nonetheless, the response was variable, and the conditions under which a response might be expected need to be further defined.

Animal Feed↗
PubMed2004

Activated lactoferrin's ability to inhibit Candida growth and block yeast adhesion to the vaginal epithelial monolayer.

OBJECTIVE: To study in vitro growth-inhibitory effects of activated lactoferrin (ALF) against vaginal isolates of Candida species and to measure the ability of ALF to block interactions of Candida albicans and Candida glabrata to the vaginal epithelial (VE) monolayer. STUDY DESIGN: In vitro effects of ALF on growth of C albicans and C glabrata in Sabouraud dextrose (SD) broth were measured as change in broth turbidity by microscale optical density assay. ALF was tested at 5 and 2.5 mg/mL concentrations against 105 yeast cell inoculum at 370 degrees C for 96 hours and compared with native lactoferrin and control (growth in broth without ALF). VE cells were isolated from human vaginal tissue biopsies to establish a functional monolayer for yeast interaction studies. ALF effects on Candida interactions with the VE monolayer were tested using 3H-thymidine-labeled yeast. Prophylactic (treatment prior to yeast inoculation onto VE) and therapeutic (treatment to detach VE-adherent yeast) potential of ALF (5 mg/mL) was evaluated against vaginal isolates of C albicans strain NTRL809A and C glabrata strain NTRL131G. RESULTS: Growth of Candida species indicated that a 105 yeast inoculum in SD broth proliferated to a stationary growth equilibrium (approximately 10(9) yeast cell density) in 18 hours (approximately 2 hours of generation time). ALF (5 mg/mL) elicited >96 hours of total stasis (100% growth inhibition) and was significantly effective against both Candida species (p < 0.0001). At 2.5 mg/mL dilution, ALF sustained total stasis activity to an average of 18 hours and 24 hours for C albicans (n = 5) and C glabrata (n = 5), respectively. Interaction studies indicated avid binding of C albicans (70 - 140 x 10(3) yeast) and C glabrata (50 - 75 x 10(3) yeast) per square centimeter of VE monolayer. ALF-treated VE showed significant blockade (p < 0.05) of yeast adhesion by 33% and 58% with C albicans and C glabrata, respectively. ALF treatment of yeast-VE complexes resulted in significant detachment (p < 0.05) of C albicans and C glabrata, by 58% and 51%, respectively. CONCLUSION: ALF is a natural fungistatic agent with potent yeast adhesion-blocking and detachment properties and is effective against the vaginal pathogens C albicans and C glabrata.

Candida albicans↗
PubMed2005

Occurrence and diversity of yeasts in the mid-atlantic ridge hydrothermal fields near the Azores Archipelago.

The yeast community associated with deep-sea hydrothermal systems of the Mid-Atlantic Rift was surveyed for the first time. This study relied on a culture-based approach using two different growth media: a conventional culture medium for yeasts supplemented with sea salts (MYPss) and the same medium additionally supplemented with sulfur (MYPssS). For the evaluation of species diversity, a molecular approach involving minisatellite-primed polymerase chain reaction (MSP-PCR) strain typing and sequence analysis of the D1/D2 domains of the 26S rDNA was followed. In the seven water samples that were studied, the number of colony-forming units per liter (cfu/L) ranged from 0 to 5940. The nonpigmented yeasts were much more abundant than the pink-pigmented ones. This disproportion was not observed in studies of other marine systems and may be due to the unique conditions of hydrothermal vents, characterized by a rich animal and microbial diversity and therefore by the availability of organic compounds utilizable by yeasts. Higher counts of nonpigmented yeast were obtained using MYPss, whereas for pink yeasts, higher counts were obtained using MYPssS. Moreover, among pink yeasts, some of the MSP-PCR classes obtained were composed of isolates obtained only on MYPssS, which might be an indication that these isolates are adapted to the ecosystems of the hydrothermal vents. Twelve phylotypes belonged to the Ascomycota and seven phylotypes belonged to the Basidiomycota. The nonpigmented yeasts were identified as Candida atlantica, C. atmosphaerica, C. lodderae, C. parapsilosis, Exophiala dermatitidis, Pichia guilliermondii, and Trichosporon dermatis, whereas the pigmented yeasts were identified as Rhodosporidium diobovatum, R. sphaerocarpum, R. toruloides, and Rhodotorula mucilaginosa. Some of the yeasts that were found belong to phylogenetic groups that include species reported from other marine environments, and eight phylotypes represent undescribed species. The new phylotypes found at Mid-Atlantic Ridge hydrothermal fields represent 33% of the total number of yeast taxa that were found.

Azores↗