Media incubation conditions

In many research and regulatory cases, data descriptive of a specimen must be associated or coordinated with the descriptions of the strains isolated from the specimens. Some common specimen data are exemplified by "total" microbial population, numbers of special groups of organisms such as coliforms, heat resistant bacteria, halophiles, psychrophiles, etc., the presence or absence of certain organisms (e.g.. Salmonella), incubation media, incubation conditions, geographic location of the specimen, physical and chemical condition of the specimen at the time of accession, and conditions of isolation of microbial strains from the specimen. 

All the test conditions are rigorously defined, including the strains to be used, the culture media for strain maintenance and test performance, product diluent, neutralization method and its validation, preparation of media, incubation conditions, material to be used, and other significant factors. 

Positive growth iHi any one, two, or three of the medium-incubation conditions was scored as a net positive. 

Name of the Medium Incubation Condition Typical Reactions References... 

The conditions which have been reported as favoring sporulation include addition of salts of metals such as manganese, chromium, nickel, etc., to the medium shaking a culture of vegetative cells of sporing aerobes with distilled water at 37°C. addition of tomato juice to a medium incubating the cultures at an appropriate temperature addition of calcium carbonate to a carbohydrate medium to prevent excessive accumulation of acid, and to maintain the pH at 5.5 or above the necessity yeen addition to the medium of certain amino acids etc. 

Fig. 5.4. LH secretion from hemipituitaries from ovariectomized rats treated during 3 d with oil (0.2 ml), estradiol benzoate (EB, 25 xg), or tamoxifen (TX, 3 mg) and incubated for 3 h with medium alone, 17/S-estradiol (E2, 10"8 M), or TX (10 7 M), in response to two consecutive GnRH challenges (10-8 M, for 15 min) at indicated time periods. Values of LH secretion from hemipituitaries of oil- and EB-injected ovariectomized rats incubated with medium alone, E2, or TX (24 hemipituitaries), and from hemipituitaries of TX-injected rats incubated with medium alone or TX (16 hemipituitaries) are represented together, as no effect of the incubation conditions was observed. Values of LH secretion from hemipituitaries of TX-injected ovariectomized rats incubated with E2 are the mean of 8 half glands. P < 0.01 versus non-EB-treated rats (modified from Sanchez-Criado et al. J Endocrinol 186 43-49,2005)...

Attention to avoid the lack of efficiency, new cultures of M. isabellina should be used and a careful control of incubation conditions (temperamre, pH and medium) is necessary. 

Vitamins and Minerals. Milk is a rich source of vitamins and other organic substances that stimulate microbial growth. Niacin, biotin, and pantothenic acid are required for growth by lactic streptococci (Reiter and Oram 1962). Thus the presence of an ample quantity of B-complex vitamins makes milk an excellent growth medium for these and other lactic acid bacteria. Milk is also a good source of orotic acid, a metabolic precursor of the pyrimidines required for nucleic acid synthesis. Fermentation can either increase or decrease the vitamin content of milk products (Deeth and Tamime 1981 Reddy et al. 1976). The folic acid and vitamin Bi2 content of cultured milk depends on the species and strain of culture used and the incubation conditions (Rao et al. 1984). When mixed cultures are used, excretion of B-complex vita-... 

Figure 7. Production of glucose and cellobiose from Avicel. The reaction mixture contained 1% Avicel PH-101, 1% Trichoderma reesei QM 9123 cellulose protein produced in a pH 3.6 culture medium, and 0.05M sodium acetate buffer, pH 5.0. Incubation conditions and analysis are...

When only limited amounts of cells are available (e.g., of human leukocytes for estimation of corticoid receptors or of human skin fibroblasts for estimation of androgen receptors) an estimation of receptors in separated cell fractions might not be feasible. Total numbers of binding sites per cell may be obtainend if different concentrations of suitable highly specific ligands are used and incubation conditions of intact cells are carefully calibrated. In addition a good separation between medium with free steroid or steroids loosely adsorbed to the cell surface and steroid bound to the receptor inside the cell is essential. 

Doolan and coworkers [18] used three compendial recovery conditions to construct survival curves for naturally contaminated medical devices soybean casein digest medium incubated at 20-25 C, the same incubated at 30-35 C. and fluid ihioglycollatc medium incubated at 30-35 C for 14 days. Three tests for sterility therefore constituted the basis for observing the presence of viable microorganisms in three replicate conditions making up one sample. 

The media controls (medium without added cells) played two roles, providing information on those compounds which are not stable in aqueous conditions, and also determining if the compound under test was soluble under aqueous conditions. As shown in Figure 3, the level of pyraclostrobin in the incubations showed a decline over a 72 hr period. In this case, no breakdown products were observed and it is likely that the pyraclostrobin precipitated out of solution. Azoxystrobin, on the other hand, remained in solution, although there was some variation in the amounts observed at the different time points indicating that there was some variability in the assay. Due to the qualitative nature of this assay, a high level of precision is not required. None of the other compounds tested were either unstable or insoluble under the incubation conditions. 

The majority of studies of fractal geometry of bacteria and unicellular fungi (yeasts) have been performed in agar culture, in which the solidity of the medium, nutrient concentration, inhibitory chemicals and incubation conditions (temperature) have been varied. With regard to bacterial pathogens, Escherichia coli, Citrobacter freundii, Klebsiella pneumoniae, Proteus mirabilis. Salmonella anatum. Salmonella typhimurium and Serratia marcescens produced colonies with Dbm values between 1.7 and 1.8 [22, 23], whereas Klebsiella ozaenae had more open colonies, Dbm = 1.6 [24]. Colony morphology is dramatically affected by nutrient supply [19, 20] and nonlethal concentrations of antibiotics [5]. For example, the fractal dimension of... 

Fig 4. Inhibition of 1-13 uptake in mouse neuroblastoma cells by antimycin and monodansylcadaverine. Confluent cells were preincubated for 30 min at 37°C in RPMI 1640 containing the inhibitor. Incubation after addition of 25pM L-T3 was for 30 min. Wells measuring 28.2 cm contained 4 ml of medium. Other conditions as in Fig 1. 

Glass vessel Volume of medium (ml) Incubation conditions Relative oxygen absorption rate... 

All strain descriptions and data on the specimen must be linked unequivocally and simply for easy retrieval. This becomes difficult to attain where multiple conditions (such as different incubation temperatures) are used with the same medium for counts of population. Total possible combinations of medium and conditions quickly become large. The number of conditions in any one study protocol are generally less than twenty. A desirable coding system... 

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