Yeast extract preparation

Yeast Food Product—The high percentage of nutritive material in yeast has led to its use as a food product since dried yeast contains 45 per cent, of albumenoids derived from the protoplasm of the ceUs. Yeast extract, prepared by heating well-washed beer yeast and evaporating in a vacuum pan to a syrupy consistency, has the appearance... 

By fractionating yeast extracts, preparations of the orotate phos-phoribosyltransferase were obtained which were free of the decarboxylase activity 14). When incubated with PP-ribose-P and orotate, these preparations formed orotidylate this product was identical with orotidylate prepared by the enzymatic phosphorylation of orotidine. The stoichiometry of the reaction was also established. 

A small fermentation tank (5,000 parts by volume capacity) was charged with 3,000 parts by volume of a culture medium (pH 6.0) comprising 3% glucose, 1 % polypepton, 0.5% yeast extract and 0.5% malt extract. The medium was sterilized by heating in a conventional manner and cooled. This medium was inoculated with 150 parts by volume of a pre[Pg.1565]

A seed culture of S. cerevisiae ATCC 24860 (American Type Culture Collection, Manassas, VA, USA) was grown in a media of 5g glucose, and 0.5 g yeast extract, respectively, 1.5 g KH2P04 and 2.25 g Na2P04 phosphate buffer up to a total volume of distilled water, 500 ml. The media was sterilised at 121 °C for 15 min. The stock culture of the microorganisms was transferred to the broth media for preparation of seed culture. 

Seed culture of Saccharomyces cerevisiae (ATCC 24860) is grown in a rich medium comprising of 1 g glucose, 0.1 g peptone and yeast extract, 0.33 g KH2P04 and 0.03 g Na2HP04 in 100 ml distilled water. The media will be autoclaved at 126 °C and 15 psig for 20 min. The stock culture from ATCC media is transferred to a prepared seed culture. The pH of... 

With the exception of Buchner s yeast extract and some comparable muscle preparations (Chapter 4), disrupting tissues often caused such damage to cells that normal metabolism was irreversibly affected. A further obstacle was that classical methods of analysis were neither sufficiently sensitive, rapid nor simple enough for the multiple measurements required to follow chemical changes in small samples of tissue. 

Among the first to describe a procedure for preparing frozen concentrated cultures were Foster (1962) and Lamprech and Foster (1963). In their process, they grew S. lactis or S. lactis subsp. diacetylactis separately at 25 °C in a tryptone-yeast extract-glucose-magnesium phosphate medium. Cells early in the maximum stationary phase (10 to 15 hr of incubation) were recovered by centrifugation, resuspended... 

Preparation and sterilization of medium Typical medium consists of corn steep liquor (4 percent to 5 percent dry weight) an additional nitrogen source such as soy meal, yeast extract, whey a carbon source such as lactose and various buffers. 

Prepare 1% yeast extract (Saccharomyces cerevisae), 1% peptone, 2% glucose and 1% agar (by weight). 

GDP-ot-D-mannose (23) is the donor substrate for mannosyltransferases [139, 146, 338-340] and the precursor of GDP-(3-L-fucose (13) [173,197, 243, 341], Based on the work of Munch-Petersen [342, 343], only crude extracts from yeast have been used for the enzymatic synthesis of labeled and unlabeled 23 and GDP-deoxymannose derivatives (Table 4) [303-305, 307, 308, 344-346] as well as for the in situ regeneration of 23 (Table 4). Common to all these approaches is the use of chemically synthesized sugar-1-phosphates as substrates for GDP-Man PP. An obvious disadvantage of using crude yeast enzyme preparations is the poor quality of the enzyme source since only fresh cells or certain batches of baker s yeast are suitable for synthesis [304, 307], GDP-Man PP was purified from pig liver and used for the synthesis of 8-Azido-GDP-Man however, the enzyme lacks absolute specificity for GDP-Man in the pyrophos-phorylysis reaction [309]. 

All chemicals were of analytical grade and obtained from Sigma (St. Louis, MO) with the exception of bacto agar, yeast extract and peptone which were obtained from Merck (Darmstadt, Germany), and D-glucose, which was obtained from VWR. Solka-floc, a delignified pine pulp serving as the cellulosic substrate, was obtained from Fiber Sales Development (Urbana, OH). For the preparation of solutions and media, distilled water was used. 

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