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At least 271 records · Page 15Linked to original sources
PubMed1986

Fed-batch cultivation of Saccharomyces cerevisiae with increased content of delta 5,7-sterols.

Cultivation of Saccharomyces cerevisiae with a linear nutrient feed was used to test the validity of a mathematical model describing changes in the physiological state of the culture. Markers of these changes were the concentrations of proteins and delta 5,7-sterols in yeast dry mass. The model was used to optimize the production of these sterols with regard to the magnitude and composition of nutrient feed.

Computers↗
PubMed1996

Differentiation of Saccharomyces cerevisiae strains isolated from fermenting musts according to their karyotype patterns.

Pulsed field electrophoresis is a suitable technique for differentiation of Saccharomyces cerevisiae strains. In this work, karyotype analysis was used to study the ecology of the wild S. Cerevisiae flora in musts in fermentation in the A.C. (Appellation Controlee) area of Valdepeñas (Spain). In order to do this, 392 colonies isolated from different vats in different cellars, where dry yeast was never used to make wines, were submitted to the Countour Homogeneous Electric Field (CHEF) technique. Each of the resulting CHEF profiles was subjected to Cluster Analysis and four main karyotypes were found in this viticultural area.

Cluster Analysis↗
PubMed1987

Controlled evaluation of trypticase soy broth with and without gelatin and yeast extract in the detection of bacteremia and fungemia.

The addition of gelatin to blood culture media has been suggested to prevent the inhibition of Neisseria meningitidis, Neisseria gonorrhoeae, Gardnerella vaginalis, and Peptostreptococcus anaerobius that is caused by sodium polyanetholsulfonate. To determine the effect of such supplementation on the overall yield of microorganisms, we compared the yield and speed of detection of clinically important microorganisms from 5422 paired 10-ml samples of blood cultured in Trypticase soy broth (TSB) containing 0.03% sodium polyanetholesulfonate (SPS) and TSB/SPS containing 1.2% gelatin and 1.0% yeast extract (mTSB). The atmosphere of incubation (open venting unit) and ratio of blood to broth (1:5) were the same for both samples. Only cultures with adequate blood sample (greater than or equal to 80% of stated volume) were compared statistically. Addition of gelatin and yeast extract resulted in inhibited growth of Enterobacteriaceae (p less than 0.001), Pseudomonas aeruginosa (p less than 0.01), fungi (p less than 0.05), and the overall set of microorganisms encountered (p less than 0.001). It delayed growth of Enterobacteriaceae (p less than 0.001) but reduced the time to recover staphylococci (p less than 0.02). Of 12 isolates of species usually inhibited by SPS, seven grew only with the addition of gelatin and yeast extract, none grew only without supplementation, and five grew in both media. Although gelatin and yeast extract may improve the yield of some specific bacteria, the routine use of these additives cannot be recommended for all blood culture media.

Adult↗
PubMed2006

Effect of nitrogen limitation on the ergosterol production by fed-batch culture of Saccharomyces cerevisiae.

The diversity and content of available nitrogen sources in the growth medium both are very important in the accumulation of ergosterol in the yeast cell membrane. Growth on the good nitrogen sources such as ammonia can harvest more yeast cells than on poor ones, but ergosterol content in those yeast cells is relatively lower. Ergosterol content, one of the most variable parameters in ergosterol production by yeast cultivation, is greatly influenced by nitrogen limitation. The aim of our work was to study how the nitrogen sources affected the membrane ergosterol content and increase the total ergosterol yield. On the premise of keeping high ergosterol content in yeast cell, the ergosterol yield was enhanced by increasing the yeast biomass. Direct feed back control of glucose using an on-line ethanol concentration monitor was introduced to achieve high cell density. Ammonia, which acted as nitrogen source, was added to adjust pH during fermentation process, but its addition needed careful control. Cultivation in 5 L bioreactor was carried out under following conditions: culture temperature 30+/-1 degrees C, pH 5.5+/-0.1, agitation speed 600 rpm, controlling ethanol concentration below 1% and controlling ammonium ion concentration below 0.1 mol/L. Under these conditions the yeast dry weight reached 95.0+/-2.6 g/L and the ergosterol yield reached 1981+/-34 mg/L.

Ammonia↗
PubMed2006

Phenotypes and fed-batch fermentation of ubiquinone-overproducing fission yeast using ppt1 gene.

Ubiquinone (UQ), a component of the electron transfer system in many organisms, has been widely used for pharmaceuticals and cosmetics. In this study, we cloned and overexpressed the full-length ppt1 (MTppt1) gene, which encodes p-hydroxybenzoate:polyprenyltransferase and ERppt1 gene, which was modified to be localized on endoplasmic reticulum in fission yeast. The yeast MTppt1 and ERppt1 transgenic lines showed about 3.7 and 5.1 times increment in UQ content and the recombinant yeasts with a higher UQ level are more resistant to H(2)O(2), Cu(2+) and NaCl, and interestingly their growth was also faster than the wild type at lower temperature. For large-scale cultivation, the direct feedback control of glucose using an on-line ethanol concentration monitor for ubiquinone production of yeast ERppt1 by high-cell-density fermentation was investigated and the fermentation parameters (e.g., dissolved oxygen, pH, ethanol concentration, oxygen uptake rate, carbon dioxide evolution rate and respiration quotient) were also discussed. After 90 h cultures, the yeast dry cell weight reached 57 gl(-1) and the ubiquinone yield reached 23 mgl(-1). In addition, plasmid stability was maintained at high level throughout the fermentation.

Biomass↗
PubMed2005

Biodiversity of Saccharomyces cerevisiae isolated from a survey of pito production sites in various parts of Ghana.

Biodiversity among Saccharomyces cerevisiae predominating the spontaneous fermentation of Dagarti pito in Ghana was assessed. Two hundred and forty-nine isolates obtained from samples of dried yeast taken from commercial pito production sites in eight geographical regions of Ghana were characterized phenotypically by colony and cell morphology as well as carbohydrate assimilation profiling. Yeast populations ranged between 10(6) and 10(8) cfug(-1). Ninety-nine percent of the isolates (247) investigated showed macro-and micro morphological characteristics typical of S. cerevisiae. Of these, 72% (179) had assimilation profiles similar to S. cerevisiae while 28% (68) had assimilation profiles atypical of S. cerevisiae or any other member of the Saccharomyces sensu stricto complex. Amplification of the region spanning the two intergenic transcribed spacers (ITS) and the 5.8S ribosomal gene (ITS1-5.8S rDNA-ITS2), followed by restriction analysis, as well as determination of chromosome length polymorphism by pulsed field gel electrophoresis (PFGE) of 25 representative isolates strongly indicated that all belonged to S. cerevisiae, notwithstanding the phenotypic differences. Sequencing of the mitochondrial cytochrome-c oxidase II gene (COX 2) and the actin-encoding gene (ACT1) of four isolates, confirmed their close relatedness to S. cerevisiae, particularly to the type strain CBS1171 (98.7%), as well as other members of the Saccharomyces sensu stricto complex. Twenty isolates selected from eight geographical regions of Ghana and investigated for their technological properties, showed different patterns of growth and flocculation but otherwise similar technological characteristica. Most of the isolates produced pito having sensory attributes, which compared favourably with commercially produced pito.

Actins↗
PubMed1977

Survey of some Fusarium moniliforme strains from different host plants for compounds possessing gibberellin-like activity.

Fifty cultures of Fusarium moniliforme were isolated from different hosts and were studied morphologically and physiologically for gibberellin production. Gibberellin production is not limited to rice isolates, since isolates from other host plants revealed also production. These isolates were highly utilizing sucrose, fructose, glucose, sorbose, maltose, mannose, xylose, and arabinose, more than lactose; also ammonium nitrate, ammonium sulphate, and ammonium tartrate were better utilized as nitrogen source than soybean, dry yeast, and corn steep liquor.

Aziridines↗