Candida

Low fermentation temperatures (10-15 0,) reportedly extends the alcohol tolerance range of C. stellata (Gao and Fleet, 1988). However, in aging wine, the interactive effects of alcohol and low ( 15°C/60°F) cellar temperature retards growth. This observation is not unique to Candidahul is characteristic of film yeast in general. 

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Page 1093 (Figure 26 9c) is adapted from crystallographic coordinates deposited with the Protein Data Bank PDB ID ICLE Ghosh D Wawrzak Z Pletnev V Z Li N Kaiser R Pangbom W Jornvall H Erman M Duax W L Structure of Un complexed and Linoleate Bound Candida Cholesterol Esterase To be published... 

Candida shehatae Candida tropicalis Candida utilis... 

Torulopsis Candida Torulopsis caroliniana Torulopsis minor Torulopsis polcherrima... 

Large-scale SCP production processes for growing yeasts of the genus Candida from hydrocarbon substrates were developed by British Petroleum Co., Ltd. and Kanegafuchi Chemical Industry, Ltd. of Japan (57). However, the 100,000-t/yr capacity plants based on these processes, and constmcted in Sardinia and Italy, were abandoned because of regulatory agency questions regarding residual hydrocarbon contents of the products (2,3). 

Table 5 presents typical operating conditions and cell production values for commercial-scale yeast-based SCP processes including (63) Saccharomjces cerevisae ie, primary yeast from molasses Candida utilis ie, Torula yeast, from papermiU. wastes, glucose, or sucrose and Klujveromjces marxianus var fragilis ie, fragihs yeast, from cheese whey or cheese whey permeate. AH of these products have been cleared for food use in the United States by the Food and Dmg Administration (77). 

Most of the bacteria, yeasts, molds, and higher fungi of interest for SCP production are deficient in methionine and must be supplemented with this amino acid to be suitable for animal feeding or human food appHcations. Also, lysine—arginine ratios should be adjusted in poultry rations in which yeast SCP is used (62). Human feeding studies have shown that only limited quantities of yeast such as Candida utilis can be added to food products without adverse effects on flavor (63). 

Another microbial polysaccharide-based emulsifier is Hposan, produced by the yeast Candida lipolytica when grown on hydrocarbons (223). Liposan is apparentiy induced by certain water-immiscible hydrocarbons. It is composed of approximately 83% polysaccharide and 17% protein (224). The polysaccharide portion consists of D-glucose, D-galactose, 2-amino-2-deoxy-D-galactose, and D-galacturonic acid. The presence of fatty acyl groups has not been demonstrated the protein portion may confer some hydrophobic properties on the complex. 

Schic saccharomyces octosporus Sporobolomyces sp. Torulaspora rosei Torulopsis Candida... 

Biosynthetic Mechanism. Riboflavin is produced by many microorganisms, m( dtm. A.shhyagossjpii A.sperigiUus sp remothecium ashbyii Candida yeasts, Debaryomjces yeasts, Hansenu/a yeasts, Picbia yeasts, A. tobactor sp, Clostridium sp, and Bacillus sp. 

Mutation. For industrial appHcations, mutations are induced by x-rays, uv irradiation or chemicals (iiitrosoguanidine, EMS, MMS, etc). Mutant selections based on amino acid or nucleotide base analogue resistance or treatment with Nystatin or 2-deoxyglucose to select auxotrophs or temperature-sensitive mutations are easily carried out. Examples of useful mutants are strains of Candida membranefaciens, which produce L-threonine Hansenu/a anomala, which produces tryptophan or strains of Candida lipolytica that produce citric acid. An auxotrophic mutant of S. cerevisiae that requires leucine for growth has been produced for use in wine fermentations (see also Wine). This yeast produces only minimal quantities of isoamyl alcohol, a fusel oil fraction derived from leucine by the Ehrlich reaction (10,11). A mutant strain of bakers yeast with cold-sensitive metaboHsm shows increased stabiUty and has been marketed in Japan for use in doughs stored in the refrigerator (12). 

Respiratory, or oxidative, metaboHsm produces more energy than fermentation. Complete oxidation of one mol of glucose to carbon dioxide and water may produce up to 36 mol ATP in the tricarboxyHc acid (TCA) cycle or related oxidative pathways. More substrates can be respired than fermented, including pentoses (eg, by Candida species), ethanol (eg, by Saccharomjces), methanol (eg, by Hansenu/a species), and alkanes (eg, by Saccharomjces lipoljticd). 

Component Bakers yeast Brewers yeast Candida sp. 

Beer taste can be spoiled by contaminating bacteria or yeasts. The most common bacteria are lactic and acetic acid producers and T ymomonas. Wild yeasts can be anything other than the intended strain S. uvarum is considered a contaminant of ale fermentations and S. cerevisiae a contaminant of lager fermentations. The common wild yeast contaminants are S. diastaticus and species of Picbia, Candida and Brettanomjces. It may be noted that the flavor of beer may be improved by the ability of yeast to adsorb bitter substances extracted from hops, such as humulones and isohumulones. 

In all fermented foods, microbes contribute as preservatives, ie, by lowering the pH and producing ethanol, or by making the food more palatable. The dehberate use of yeasts as food in themselves is less common. Small beer, the sediment from beer, has been traditionally used as a vitamin supplement for infants. Beginning in 1910, dried, spent brewers yeast was developed as a food, and Candida utilis was used as a food supplement in Germany during World War II. 

Candida utilis is grown on sulfite waste Hquor in Western Europe and North America, on sugar cane molasses in Cuba and Taiwan and on ceUulose acid hydrolysates in Eastern Europe and the former Soviet Union. C. ///i/if utilizes hexoses, pentoses, and many organic acids. Sulfite Hquor from hardwoods contains 2—3% fermentable sugars of which 20% are hexoses and 80% pentoses in softwood Hquors the proportions are reversed. The SO2 must be stripped out to allow yeast growth, which is carried out in large, highly-aerated fermentors. Eor continuous fermentations, carried out at pH 4 and 30°C, the dilution rate is 0.27—0.30 (34). 

Both alkanes and gas oil can be used as carbon and energy sources. Commercially, Candida tropicalis and Candida lipolytica have been used (35,36). The fermentation contains two immiscible Hquid phases (the alkane and the water) the semisoHd yeast and the gaseous air phase. In contrast to yeasts grown on carbohydrates, where maximum yields are 50%, yeasts grown on alkanes generally give yields of 95—105% based on the weight of the alkane. 

Nystatin is mainly used to treat vaginal and oral infections and localized skin lesions, including Candida intertrigo and Candida nappy dermatitis. It may also be used as prophylaxis during treatment with antibiotics. 

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