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Contamination on an agar plate. An agar plate is a Petri dish that contains a growth medium solidified with agar, used to culture microorganisms. Sometimes selective compounds are added to influence growth, such as antibiotics. [1] 96 pinner used to perform spot assays with yeast, fungal or bacterial cells
An agar plate – an example of a bacterial growth medium*: Specifically, it is a streak plate; the orange lines and dots are formed by bacterial colonies.. A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation [1] or small plants like the moss Physcomitrella patens. [2]
Once a plate has been successfully prepared, plate count agar cells will grow into colonies which can be sufficiently isolated to determine the original cell type. The colony-forming unit (CFU) is an appropriate description of the colony's origin. In plate counts, colonies are counted, but the count is usually recorded in CFU.
Stab cultures are similar to agar plates, but are formed by solid agar in a test tube. Bacteria is introduced via an inoculation needle or a pipette tip being stabbed into the center of the agar. Bacteria grow in the punctured area. [11] Stab cultures are most commonly used for short-term storage or shipment of cultures.
Bacilli usually have a rod or cylinder shape. Examples include Listeria, Salmonella typhimurium, Yersinia enterocolitica, and Escherichia coli. Yersinia enterocolitica colonies growing on XLD agar plates Escherichia coli Color-enhanced scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells
Green tea-flavored yōkan, a popular Japanese red bean jelly made from agar A blood agar plate used to culture bacteria and diagnose infection. Agar (/ ˈ eɪ ɡ ɑːr / or / ˈ ɑː ɡ ər /), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from “ogonori” and “tengusa”.
In the laboratory, bacteria are usually grown using solid or liquid media. [117] Solid growth media, such as agar plates, are used to isolate pure cultures of a bacterial strain. However, liquid growth media are used when the measurement of growth or large volumes of cells are required.
The addition of peptones into the agar provides the growth factors required by the bacteria to grow. [7] Casein also provides a source of amino acids for organisms with fastidious growth requirements such as Lactobacillus brevis. [8] It contains the antibiotics colistin and nalidixic acid which inhibit the growth of many gram-negative bacteria.