Microbiological growth media

There are many types of biological growth media commercially available. The Pulp and Paper Research Group has selected media for the cultivation of a variety of microorganisms typically found in Pulp and Paper Systems. Media recommendations for different microorganisms are outlined below. 

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A number of general microbiological growth media are available and may be used in a process simulation program. In general, when selecting a medium for use, the following considerations should be made ... 

The conduct of aseptic processing validation ordinarily requires the use of a microbiological growth medium in lieu of the product. The PDA/PhRMA joint task force of Validation of Sterile Bulk Processes has outlined some process simulation methodologies which do not... 

For aqueous liquid products the placebo most commonly used is a liquid microbiological growth medium (broth). For solid dosage form, placebos such as lactose, mannitol, and polyethylene glycol may be filled and microbiological growth medium added afterwards,... 

Figure 1. Specific activity of cutinase as a function of sole carbon source in the growth medium. The T-8 strain of F. solani was grown on 0.5% acetate (o), 1.5% acetate (A), or 1.5% glucose ( ) as the sole carbon source. (Reproduced with permission from Ref. 13. 1986, American Society for Microbiology.)...

MILK AND MILK PRODUCTS. Intricate chemical and microbiological problems arise in the production, processing, and distribution of milk products. Milk is a complex mixlure of fat (40 ). protein (3.5 3 I. carbohydrate (4.8rf) and mineral components t().7 ) and is an excellent hacleria growth medium hence the need for care and cleanliness in handling. 

In direct inoculation, the product samples are put aseptically into the microbiological recovery medium and incubated. Clearly this approach is only suited to products that are not likely to be inhibitory to the growth of microorganisms in the recovery medium. An incubation period of 14 days is specified. 

Since the introduction of parenteral nutrition in hospital care the potential microbiological risks associated with the manufacture, preparation, and administration of these products have abated but not disappeared (133,152). Fatal infectious complications still occur. The parenteral nutrition mixture is a good growth medium for microorganisms, more conducive to microbial growth than glucose or amino acid solutions. Storage of mixtures... 

Casadei, M.A., Esteves de Matos, R., Harrison, S.T., and Gaze, J.E. 1998. Heat resistance of Listeria monocytogenes in dairy products as affected by the growth medium. Journal of Applied Microbiology 84 234-239. 

Usually purified water (Aqua purificata) is used. Because of the chemical and microbiological quality it is preferred over potable water (see Sect. 20.3.1) although the taste of potable water may be better due to presence of ions. Water is a good growth medium for micro-organisms, so aqueous oral liquids generally have to be preserved, see Sect. 5.4.9. 

As complexity increases so does risk of microbiological contamination, although there is little evidence to support this. Other risk factors for microbiological contamination include the extent to which the product is a good growth medium, and the time between its preparation and administration to the patient. 

Incubation of the food extract at several dilution levels with the growth medium and microbiological culture... 

Chemically, graphite is ejqpected to be a stable material in the disposal environment, being resistant to oxidative corrosion across a wide range of conditions, and providing an unattractive medium for microbiological growth. Thus releases of carbon-14 from such wastes are expected to be low. 

McKinlay, J.B., Zeikus, J.G., Vieflle, C., 2005. Insights into Actinobacillus succinogenes fermentative metabolism in a chemicaUy defined growth medium. Applied and Environmental Microbiology 71 (11), 6651-6656. 

Long-chain unsaturated fatty acids in small amounts quantitatively inhibit growth of Lactobacillus casei, the bacteriostatic effect being reversed by the addition of vitamin D to the growth medium. Kodicek (1950) proposed a microbiological assay based upon this observation. The bacterial system mimicked several of the criteria of mammalian rickets, such as response to vitamin D, replacement of vitamin D effect with calcium ions, interrelationship with phosphate concentration, and the toxic effects of excess vitamin D. This method is, however, not sensitive for small amounts of the vitamin. The fact that unsaturated fatty acids bind calcium has to be considered as a likely mechanism for inhibition of bacterial growth. 

The trays are charged with the hot medium and, on cooling to 30°C, the inoculum is added. Two days are normally required for germination and growth and towards the end of this period the pH drops. These first two days are crucial in a microbiological sense because it is here that problems of contamination are most likely to occur. 

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