Question

what are the purposes of media preparation

Answer 1

Bacterial Culture Media:
It is necessary to provide an appropriate biochemical and biochemical environment for the spread of any bacteria for any purpose. The biochemical (nutrient) environment has become available as a culture medium and has developed a large variety and culture media with different benefits and uses based on the specific needs of particular bacteria (especially researchers). Went. Culture medium is used in the isolation and maintenance of pure cultures of bacteria and they are also used to identify bacteria according to their biochemical and physical properties.
The purpose of bacterial cultivation and culture media varies widely. Liquid media is used for the development of pure batch cultures, while solid media is widely used for pure culture separation, viable bacterial populations and other purposes. A common gelling agent for solid or hemispherical media is hydrocarbon derived from agar, red algae. Due to its unique physical properties (it melts at 100oC and cools up to 40oC, the temperature at which it gels) is liquid and because it is not metabolized by most bacteria. It is therefore relatively passive as a medium component; It only contains (gels) nutrients in the aquarium solution.
Culture media can be classified into several categories based on their structure or use. Chemically defined (synthetic) medium in which the exact chemical composition is known. A complex (undefined) medium in which the exact chemical constitution of the medium is unknown. Definitive media are usually composed of biochemical purified from the shelf; Complex media usually contain biological substances such as blood or milk or yeast extract or beef extract, the exact chemical composition of which cannot be clearly determined. A defined medium is a minimum medium if it provides only the exact nutrients (including any growth factors) that the organism needs for growth. The use of a defined minimum medium requires the researcher to know the exact nutritional requirements of the organisms in question. Chemically defined medium is valuable for microbiological minimum nutrient requirements, culturing cultures, and a variety of physiological studies. Complex media usually provide the full range of growth factors that an organism needs, so they can be more easily used to cultivate unknown bacteria or bacteria that have complex nutritional needs (ie, organisms that require a lot of growth factors, known or unknown). Complex media are commonly used for bacterial pathogens and other rapid bacterial cultivation.
Most pathogenic bacteria in animals, which are adapted to the growth of animal tissues, require complex media for their growth. Blood, serum, and tissue extract are often added to culture media for the cultivation of pathogens. However, for some unintentional pathogens such as Treponeoma palidium, agents of syphilis and Mycobacterium leprae, the cause of leprosy, artificial culture medium and conditions have not been established. This fact fails the ability to do basic research on these pathogens and the diseases that cause them.

Other elements used in the creation of culture media are the principles of selection and promotion. Selective media means that a component (s) attached to it inhibits or inhibits the growth of certain types or species of bacteria and / or promotes the growth of the desired species. The physical conditions of the culture medium, such as pH and temperature, can also be adjusted for selection of organisms capable of growing under some of these conditions.
Culture medium is also a differential medium if the researcher is allowed to distinguish between different types of bacteria based on some observable characteristics in their growth pattern. Therefore, Staphylococcus aureus, the differential medium selected for the isolation of the most common bacterial pathogens in humans, has a high salt concentration (which can withstand the stop), which inhibits many other bacteria, fermented sugar sources. Manganese, and pH indicator color. From the clinical models, only the staff grows. S. Based on its ability to ferment mannitol, it is differentiated from Aureus S. epidermidis (a non-pathogenic component of normal flora). Mannitol-fermented colonies (S. aureus) produce acids that react with the indicator color to form a color halo around the colonies; Mannitol non-fermentants (S. epidermidis) use other fermentation agents in the medium for growth and do not form corona around their colonies.
A culture medium gives a slightly different twist. There are certain types of components in a culture medium that allow the growth of certain types or species of bacteria because they can only use this part from their environment. However, culture media may have selected characteristics. A culture medium for nonsymbiotic nitrogen fixing bacteria leaves a source of nitrogen added to the medium. Medium is vaccinated with a potential source of this bacteria (such as a soil sample) and incubated in the atmosphere, N2 is the only source of available nitrogen. The selective enrichment medium for the development of extreme halophiles (halococcus) contains about 25% salt [NaCl], which requires high halophiles and which inhibits the growth of all other satellites.

Fungal culture
Developing fungi from a patient sample is the most direct and usually decisive tool for establishing fungal infection diagnosis. A fungus, including blood, cerebrospinal fluid, pus, urine, tissue, respiratory specimens (sputum, bronchoscopy lavage), pleural, pericardial or peroneal fluid, skin scratches, hair, nail clipping, oral or vaginal specimens. Can produce. The processing of these samples may include centrifugation or softening / liquidation to allow diffusion of the sample into the agar medium. Most laboratory manuals and specific methods explain how to do this, although very few comparative studies compare one method to another.
The importance of media selection
The yield of many fungi is greater than the live culture of samples known as media fungal media. For some fungi, bacteria in cultures are always or almost always negative in the media, for example histoplasma, mucorless, and coccidioides spp. The culture of Aspergillus spp. % 30% less effective than fungal media in bacterial media [1].
The general-purpose medium used for fungal culture is Subauder dextrose, malt extract and, less commonly, brain heart infusion medium. To avoid contamination of the medium by bacteria, chloramphenicol is used, but inhibits the growth of actinomyces, while others grow well on Saboudre dextrose agar. Cyclohenside is added to reduce the frequency of environmental fungal growth, but it also reduces the yield of many opportunistic fungi, including Aspergillus spp. Cryptococcus neoformans and mucorals are different. So if cyclohydride is used, an agar plate that does not have it should also be used in parallel.
Media for selected culture and media identity
Some additional specific media can be directly used on the samples to allow the identification of Cryptococcus spp. Chromogenic agar for direct, partial detection of Candida spp. In HIV cultures or from HIV patients.