Yeast

About: Yeast is a research topic. Over the lifetime, 31777 publications have been published within this topic receiving 868967 citations. The topic is also known as: yeasts.

Fuel alcohol production: Effects of free amino nitrogen on fermentation of very-high-gravity wheat mashes. [Saccharomyces cerevisiae]

Abstract: Although wheat mashes contain only growth-limiting amounts of free amino nitrogen, fermentations by active dry yeast (Saccharomyces cerevisiae) were completed (all fermentable sugars consumed) in 8 days at 20{degree}C even when the mash contained 35 g of dissolved solids per 100 ml. Supplementing wheat mashes with yeast extract, Casamino Acids, or a single amino acid such as glutamic acid stimulated growth of the yeast and reduced the fermentation time. With 0.9% yeast extract as the supplement, the fermentation time was reduced from 8 to 3 days, and a final ethanol yield of 17.1% (vol/vol) was achieved. Free amino nitrogen derived in situ through the hydrolysis of wheat proteins by a protease could substitute for the exogenous nitrogen source. Studies indicated, however, that exogenously added glycine (although readily taken up by the yeast) reduced the cell yield and prolonged the fermentation time. The results suggested that there are qualitative differences among amino acids with regard to their suitability to serve as nitrogen sources for the growth of yeast. The complete utilization of carbohydrates in wheat mashes containing very little free amino nitrogen presumably resulted because they had the right kind of amino acids.

Growth of Natural Yeast Flora during the Fermentation of Inoculated Wines.

Abstract: The growth of yeasts that occur naturally in grape juice was quantitatively examined during the fermentation of four wines that had been inoculated with Saccharomyces cerevisiae. Although S. cerevisiae dominated the wine fermentations, there was significant growth of the natural species Kloeckera apiculata, Candida stellata, Candida colliculosa, Candida pulcherrima, and Hansenula anomala.

A Method of isolating Protoplasts from Yeast

Abstract: A NEW approach to the structure and functions of the cell surface of certain bacteria was revealed when Weibull1 showed that, in the presence of sucrose, lysozyme dissolves the cell-wall, leaving the protoplast essentially intact. Various attempts have since been made to isolate protoplasts from bacteria normally insensitive to lysozyme2 and also from yeast. Thus Necas3 showed that spontaneously autolysing yeast gave rise to a small extent to structures which, superficially at least, resembled protoplasts.

3-phosphoglycerate kinase from rabbit sceletal muscle and yeast.

Abstract: Phosphoglycerate kinase, isolated from rabbit muscle in highly purified crystalline form, was compared in terms of chemical, physical and kinetic properties to yeast phosphoglycerate kinase A summary of the data is presented Both proteins are composed of a single polypeptide chain, and in electrophoresis only one band was found The N-terminus is masked The C-terminal amino acid of the muscle enzyme is valine Muscle and yeast enzyme have nearly identical molecular weights, Michaelis-Menten constants, optimal pH values and Vmax On the other hand, they differ significantly in their amino acid composition, especially in the content of sulfur and aromatic amino acids, in electrophoretic mobility and in heat stability The muscle enzyme has an essential SH group The single SH group of the yeast enzyme is apparently without importance for enzyme activity Differences in the same direction as those observed with yeast and muscle phosphoglycerate kinase are discussed in connection with other glycolytic enzymes from the same organisms