Medium nutrient composition

The cell plasma membrane separates the cell cytoplasm from the external medium. The composition of the cytoplasm must be tightly controlled to optimize cellular processes, but the composition of the external medium is highly variable. The membrane is hydrophobic and impedes solute diffusion. But it also facilitates and regulates solute transfers as the cell absorbs nutrients, expels wastes and maintains turgour. 

The medium utilized to provide complete nutrition for the growth of different cell types is based on a standard minimum essential nutrient composition. Most media consist of a sugar source, minerals, vitamins, and amino acids. Serum, such as fetal bovine serum, commonly supplements the medium to enhance cell growth. Growth factors and cytokines are utilized to accelerate cell growth through interaction with specific cell receptors. Differentiation inducers are added to direct the differentiation pathway of stem cells. Impor-... 

When inoculating a fresh medium, the cells encounter an environmental shock, which results in a lag phase. The length of this phase depends upon the type of organism, the age and size of the inoculum, any changes in nutrient composition, pH and temperature. When presented with a new nutrient the cell adapts itself to its new environment and normally produces the required enzyme. 

In the extraction of sugarcane, blackstrap molasses is the third and final extraction. It has more of the minerals than light or medium molasses. Blackstrap has a strong flavor, so usually only small amounts are eaten. The nutrient composition of blackstrap molasses is given in Eood Composition Table E-21. 

Nutritional Requirements. The nutrient requirements of mammalian cells are many, varied, and complex. In addition to typical metaboHc requirements such as sugars, amino acids (qv), vitamins (qv), and minerals, cells also need growth factors and other proteins. Some of the proteins are not consumed, but play a catalytic role in the cell growth process. Historically, fetal calf semm of 1—20 vol % of the medium has been used as a rich source of all these complex protein requirements. However, the composition of semm varies from lot to lot, introducing significant variabiUty in manufacture of products from the mammalian cells. 

A slant of S. antibioticus ATCC 11891 was cultivated on agar under controlled conditions in order to develop spores for the purpose of inoculating a nutrient medium having the following composition 20 g Cerelose (dextrose hydrate), 15 g soybean meal, 5 g distillers solubles, 10 g cornmeal, and tap water, in a sufficient amount for a 1,000-ml solution, adjusted to pH 7.0 to 7.2 with potassium hydroxide. 

As described in U.S. Patent 2,916,485 12 liters of a nutrient medium having the following composition is placed in a 30 liter fermentor equipped with stainless steel fittings including sparger, impeller, baffles and sampling lines and the medium is sterilized by heating at 121°C for two hours. 

Sterile agar slants are prepared using the Streptomyces sporulation medium of Hickey and Tresner, J. Bact., vol. 64, pages 891-892 (1952). Four of these slants are inoculated with lyophilized spores of Streptomyces antibioticus NRRL 3238, incubated at 28°C for 7 days or until aerial spore growth is well-advanced, and then stored at 5°C. The spores from the four slants are suspended in 40 ml of 0.1% sterile sodium heptadecyl sulfate solution. A nutrient medium having the following composition is then prepared 2.0% glucose monohydrate 1.0% soybean meal, solvent extracted, 44% protein 0.5% animal peptone (Wilson s protopeptone 159) 0.2% ammonium chloride 0.5% sodium chloride 0.25% calcium carbonate and water to make 100%. 

Typically, the manufacture of a batch of biopharmaceutical product entails filling the production vessel with the appropriate quantity of purified water. Heat-stable nutrients required for producer cell growth are then added and the resultant medium is sterilized in situ. This can be achieved by heat, and many fermenters have inbuilt heating elements or, alternatively, outer jackets through which steam can be passed in order to heat the vessel contents. Heat-labile ingredients can be sterilized by filtration and added to the fermenter after the heat step. Media composition can vary... 

Encapsulated within the pores of soils are aqueous solutions, the so-called soil solutions. Radio-tracer experiments have shown that there is a rapid, dynamic equilibrium between metal ions in the soil phase and the soil solutions. Hence, the soil solution is regarded as the transport medium for moving the essential nutrients from soils to plants. The soil solutions are highly variable in composition and properties, e.g. the pH can vary over the range 2-11. Alkaline soils are notorious for causing metal ion deficiency in plants, principally because many of the micronutrients form insoluble hydroxides and so are biologically unavailable. 

Natural media are those used on the basis of experience and not on the basis of exact knowledge of their composition and action. Natural or complex media usually contain peptones, beef extract, or yeast extract. When a solid medium is desired, a solidifying agent such as gelatin or agar may be incorporated into the medium. Examples of a relatively simple liquid and a solid medium that support the growth of many common heterotrophs are nutrient broth and nutrient agar. Their composition is as follows ... 

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