Yeast elemental composition

As an average, the composition CHj 8O0 5N025 often suffices. The average elemental composition of bacteria is different from that of yeasts or fungi, of which the approximate compositions are listed in Table 8.3 ... 

Nicolini, G. and Larcher, R. (2003) Evidence of changes in the micro-element composition of wine due to the yeast strain. Riv. Vitic. Enol, 56(4), 45-48. 

The average biomass used to represent many yeasts and bacteria has an elemental composition, on a C-moIe basis, of CH. sOo.5No.2. Compute its generalized degree of reduction, and estimate its Gibbs energy and heat of combustion. 

In Illustration 15.9-4 we considered the production of ethanol from glucose using the yeast Saccharomyces cerevisiae. In that illustration 0.451 C-moles of ethanol and 0.235 C-moles of biomass of elemental composition CHi.80o.56No.n were produced per C-mole of glucose, using 0.0399 moles of ammonia. Assuming the inlet and outlet streams are maintained at 25°C, and that the work input is negligible, what is the heat load on the reactor ... 

A few studies have been carried out on the trace element composition of nonvascular plants. Schwarz (835) has reported briefly on the selenium content of yeast, and Wey (993) used activation analysis to determine the Mn and Cu contents of chlorella cells. Marine algae have been analyzed for As, Ba, Br, Cs, Co, Ca, I, Hg, Mo, Rb, Re, Sr, U, V, and W by Fukai and Meinke (302,303), Hamaguchi et al. (384), Lunde (572) and Stevenson et al. (919). Merlini and co-workers (609,610) report on the use of nondestructive activation analysis to determine some of these elements in microplankton from fresh water aquatic systems. 

The elemental and vitamin compositions of some representative yeasts are Hsted in Table 1. The principal carbon and energy sources for yeasts are carbohydrates (usually sugars), alcohols, and organic acids, as weU as a few other specific hydrocarbons. Nitrogen is usually suppHed as ammonia, urea, amino acids or oligopeptides. The main essential mineral elements are phosphoms (suppHed as phosphoric acid), and potassium, with smaller amounts of magnesium and trace amounts of copper, zinc, and iron. These requirements are characteristic of all yeasts. The vitamin requirements, however, differ among species. Eor laboratory and many industrial cultures, a commercial yeast extract contains all the required nutrients (see also Mineral nutrients). 

Zn (0.14 mg/L), as well as for Co (1.7 xg/L) if considered with respect to a very low normal content in wine. In any case, it is interesting to note that even the winemaker s simple choice of the yeast strain to be used for fermentation may affect the final composition of wine elements. 

In this case, the spike added first is used as a tracer, for example, in metabolic studies, and the second for quantification of the elemental species. Meija et al. [99] investigated the redox interconversion reaction between Cr(III) and Cr(VI) in yeast using °Cr-emiched Cr(III) and Cr-enriched Cr(VI) by least-squares ion intensity-based IPD. They found that the results were in exact agreement with conventional isotope dilution calculations. An example in which IPD was applied for metabolism studies is the determination of the metabolism of butyltin compounds in rats [100]. Sn-labeled MET, Sn-labeled DBT, and Sn-labeled TBT dissolved in tap water were administered orally to the animals. Degradation of the butyltin compounds was studied in different organs by least-squares IPD and their concentrations were determined via reverse isotope dilution analysis using the corresponding compounds of natural isotopic composition as spikes. 

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