Assimilation tests

L. J. Wickerham, J. Bacteriol., 52 293-301 (1946). A critical evaluation of the nitrogen assimilation tests commonly used in the classification of yeasts. 

To establish the assimilation characteristics of microbes, the cells were fixed to an oxygen electrode and contacted with the substrates to be tested (Hikumaetal., 1980d). In contrast to conventional assimilation tests requiring cultivation of 24-72 h the sensor assay needed only 30 min. The physiological state of the cells can be determined in a similar manner (Riedel et al., 1985b). 

Assimilation tests for carbon compounds use yeast nitrogen base (YNB) without carbon sources, and the assimilation test for nitrogen compounds use yeast carbon base (YCB) without assimilable nitrogen sources. For the tests described, YNB without amine acids and ammonium sulfate is used (Anonymous, 1984). Carbon sources normally examined include a number of pentoses, hexoses, disaccharides, trisaccharides, polysaccharides, alcohols, organic acids, and glycosides as specified by Yarrow (1998). Nitrogen sources commonly tested include nitrate, nitrite, ethyl-amine hydrochloride, cada-verine dihydrochloride, L-lysine, imidazole, glucosamine, creatine, and creatinine. When nitrite is used as a test compound, it is necessary to adjust the pH of the medium to 6.5 because toxic nitrous acid is formed at pH <6.0. 

Wickerham, L.J. and Bnrton, K.A. (1948) Carbon assimilation tests for the classification of yeasts. Journal of Bacteriology, 56 363-371. 

The resulting field at the contact point with the material to be tested can be assimilated to a material point. The influence of the lateral field is considerably minimized. 

This section covers only the tests that are essential on a completed motor, irrespective of the manufacturing procedure and stage quality checks. If ISO 9000 guidelines are assimilated, practised and enforced by a manufacturer so that a customer s trust is obtained, a final pre-despatch inspection by the customer may not be necessary. The customer, having gained confidence in the practices and Quality Assurance Systems of the manufacturer, may issue an authorization to the manufacturer to despatch the material under their own inspection certificate, rather than an inspection by the customer. We discuss below the test requirements procedure and the acceptance norms prescribed by various national and international standards for such machines and adopted by various manufacturers. 

The ANN was able to assimilate the cause-effect relationship of the density of the ester, its structure and temperature. The training and testing results are shown in Fig. 10-14 for individual ester series. The network with the proposed training routine converged in less than 100 iterations for all the esters. 

Once the model was complete, it was adjusted to a steady state condition and tested using historic carbon isotope data from the atmosphere, oceans and polar ice. Several important parameters were calculated and chosen at this stage. Sensitivity analysis indicated that results dispersal of the missing carbon - were significantly influenced by the size of the vegetation carbon pool, its assimilation rate, the concentration of preindustrial atmospheric carbon used, and the CO2 fertilization factor. The model was also sensitive to several factors related to fluxes between ocean reservoirs. 

A variety of commercial kits and automated systems are available to test the abilities of bacteria to assimilate, ferment, decarboxylate, or cleave selected organic compounds.46 Their reliability for species identification is usually greater with cultures from clinical samples, where a limited number of bacteria are commonly encountered, and less with environmental soil and water samples, where a great many uncommon or previously unidentified species not in the database are likely to be present.29,45 Additional tests beyond those found in the commercial kits may be necessary for example, the hydrolysis of various nitriles and amides is useful for identifying Rhodococcus spp.47 Some commercial kits for clinical use feature antimicrobial susceptibility testing.21... 

The indicator molecule serves to assess the state of health of the cultured cells. The dye neutral red is often used (healthy cells assimilate the dye, dead cells do not). The major drawback to such systems is that they do not reflect the complexities of living animals and, hence, may not accurately reflect likely results of whole-body toxicity studies. Regulatory authorities are (rightly) slow to allow replacement of animal-based test protocols until the replacement system is proven to be reliable and is fully validated. 

Tests show that the presence of soil reduces the toxicity of copper to the soil-dwelling nematode Caenorhabditis elegans copper toxicity to nematodes increases with increasing densities of bacteria and increasing concentrations of sodium chloride or potassium chloride (Donkin and Dusenbery 1993). Terrestrial isopods efficiently assimilate and store copper as detoxihed granules in the hepatopancreas this activity is in contrast to many species of marine crustaceans that are unable to assimilate, detoxify, or otherwise regulate copper (Weeks and Rainbow 1993). 

Attention should be given to the layout of the test report or calibration certificate, especially with regard to the presentation of the test or calibration data and ease of assimilation by the... 

On a comparative basis, Pu, Am and Cm tend to be assimilated from the G.I. tract into the internal body in the following order Pu < Am < Cm (Figure 3). When Pu-nitrate is inhaled in aerosol form by dogs (27), daughter Am-241 tends to be transported more from lung and lymph nodes to liver than does plutonium (Fig. 3). Another example of potential Am enrichment is that when the rumen contents of fistulated cattle grazing on the Nevada Nuclear Test Site were leached with simulated gastric fluids,... 

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