Whats the basic defferences between all culture media And which culture media would use for which???? Sir I have used nutrient agar for fungus culture….
Before i use PDA for culture it was gud…. But i found lots of bacterial contamination in my Nutrient agar culture…. Does the composition of beef extract hampers the groeth of fungus and favours bacteria instead. Hello I have a question. If a leg wound is cultured and it is put on a nutrient agar, Selective agar and Differential Agar what are expected to show?
I streaked out from sweet potato steep water and I had both red colonies and white colonies that turned nutrient agar kind of green. Please what kind of organisms are these. They areboth staining gram positive. Basal media 2. Enriched media 3. Selective media 4. Enrichment media 5. Differential media. Just list put techniques name so that i could learn it from basics. Could u tell me what are the microbial techniques? Just list out the techniques name so that i could learn it from basics.
Save my name and email in this browser for the next time I comment. Composition of Nutrient Agar 0. Distilled water Water is essential for the growth of and reproduction of micro-organisms and also provides the medium through which various nutrients can be transported.
Preparation of Nutrient Agar 1. Suspend 28 g of nutrient agar powder in 1 litre of distilled water. Heat this mixture while stirring to fully dissolve all components.
Autoclave the dissolved mixture at degrees Celsius for 15 minutes. Once the nutrient agar has been autoclaved, allow it to cool but not solidify. Replace the lid of each Petri dish and store the plates in a refrigerator. Uses of Nutrients Agar 1. It is frequently used for isolation and purification of cultures. Pictures Four nutrient agar plates growing colonies of common Gram negative bacteria.
Source: Wikipedia. Suspending 28 g of nutrient agar powder in 1 litre of distilled water. That was for 1 plate For 6, it will be 4. These bacteria would eventually grow and flourish if the medium were not sterilized, that is, if these unwanted microbes were not destroyed. Sterilization procedures eliminate all viable microorganisms from a specified region. Culture dishes, test tubes, flasks, pipettes, transfer loops, and media must be free of viable microorganisms before they can be used for establishing pure cultures of microorganisms.
The culture vessels must be sealed or capped with sterile plugs to prevent contamination. There are various ways of sterilizing the liquids, containers, and instruments used in pure culture procedures; these include exposure to elevated temperatures or radiation levels to kill microorganisms and filtration to remove microorganisms from solution. Media preparation for the microbiology laboratory involves the use of an autoclave for sterilization, which permits exposure to high temperatures for a specified period of time.
Much of the time spent in preparation for the bacteriology laboratory involves preparing the media for growing bacteria; that is, mixing and sterilizing the growth media in suitable sterile culture vessels. In this exercise you will prepare a complex medium. However, conventional culture techniques often fail to support the growth of extremophiles under high temperature and pressure conditions, low or high pH values etc. This finding provided a versatile platform to support the growth of a wide number of extremophiles including acidophiles, alkaliphiles, thermophiles, acidothermophiles and alkalithermophiles under extreme physiochemical conditions in laboratory.
In the earlier days, isolation of bacteria for preparation of pure culture was very difficult in liquid media. Often any attempt to prepare pure culture using liquid media would result in contamination because of the slow and tedious steps. Thus came the need of a solid media, which was achieved by adding a gelling agent to the liquid broth. The first gelling agent used was gelatin by Robert Koch in to prepare solid medium.
These problems led to the discovery of an alternative gelling agent agar. Angelina Fanny Eilshemus, wife of Walther Hesse, an associate of Koch, first proposed the use of agar as a substitute to prepare solid culture medium.
Additionally agar does not have any toxic effect on bacteria, has good diffusion characteristics and is not digested by most bacteria. Agar is also found to have good clarity and is metabolically inert. But on the flip side, agar is not suitable for culturing thermophilic microbes and inhibits PCR in a concentration dependent manner [ 6 ].
Besides, high cost of agar has made research work very expensive and due to its high usage in laboratories, the natural resources of agar i. Gelidium sp. Any organism has an optimal pH at which it grows the best. Alteration of this pH value leads to undesirable growth. Each species of microbe is divided into three types on the basis of its own characteristic range of pH values in which it grows and reproduces best.
Although we know that the general pH range for most bacteria is 5 to 9 optimum 7 , they can be acidophilic pH range from 0 to 5. Just like other organisms, microorganisms also need a physiological pH inside their cells. The ability to survive in extreme pH either high or low, depends on their ability to neutralize the environmental difference with the physiological pH [ 8 ]. Microorganisms like Helicobacter pylori mostly are found in stomach in very acidic conditions, so to maintain their environmental differences they produce urease, an enzyme that degrades urea and decreases the acidity [ 9 ].
There are other bacteria that are specialized to live in alkaline pH, for instance near black smokers, geological fountains of minerals that shoot highly alkaline minerals into the ocean [ 10 ].
The change in the acidic or alkaline conditions of the medium is indicated by a color change using pH indicators. They are used in culture media to differentiate between the different groups of microorganisms based on their acid or alkali producing properties. Osmolarity is an important parameter for the formulation of any culture media as it helps the media resemble the natural environment of the cells for their proper growth.
Certain organic solutes known as osmoprotectants are used to make the cells resistant towards a wide range of osmotic tension. So far, in microbial growth osmolarity has not been systematically explored as a parameter to culture unculturable and difficult to culture microorganisms. Several metabolically active microorganisms that can be seen under microscope, cannot be cultured in the laboratory conditions.
To grow these unculturable microorganisms novel techniques have been implemented in recent times. Some bacteria exhibit co-culture dependence. They only grow in the presence of helper microorganisms, and present a problem of a need of mixed culture. The current knowledge base of microbial growth media is a limiting factor in culturing various microorganisms.
Broadening the knowledge base will require extensive research in the field and help achieve affordable culturing of the unculturable microorganisms. Better control of pH, use of better pH probes and control over osmolarity is largely missing from current microbial media. We expect to see a systematic research in this direction to culture presently unculturable microorganisms.
A look into animal cell culture, which has been focus of more recent research, can guide further development of microbial media. It is possible that alternative gelling agents can support the growth of microorganisms that do not grow on agar.
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