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Furthermore, the term culture is more generally used informally to refer to "selectively growing" a specific kind of microorganism in the lab. It is often essential to isolate a pure culture of microorganisms. A pure (or axenic) culture is a population of cells or multicellular organisms growing in the absence of other species or types.
One significant cell-line cross contaminant is the immortal HeLa cell line. HeLa contamination was first noted in the early 1960s in non-human culture in the USA. Intraspecies contamination was discovered in nineteen cell lines in the seventies. In 1974, five human cell lines from the Soviet Union were found to be HeLa.
Human interactions with microbes include both practical and symbolic uses of microbes, and negative interactions in the form of human, domestic animal, and crop diseases. Practical use of microbes began in ancient times with fermentation in food processing ; bread , beer and wine have been produced by yeasts from the dawn of civilisation, such ...
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]
The microorganism must be found in abundance in all organisms suffering from the disease but should not be found in healthy organisms. The microorganism must be isolated from a diseased organism and grown in pure culture. The cultured microorganism should cause disease when introduced into a healthy organism.
In the 1880s, Robert Koch discovered that microorganisms caused the diseases tuberculosis, cholera, diphtheria, and anthrax. Because microorganisms include most unicellular organisms from all three domains of life, they can be extremely diverse. Two of the three domains, Archaea and Bacteria, only contain microorganisms.
Thus, the plate can be used either to estimate the concentration of organisms in a liquid culture or a suitable dilution of that culture using a colony counter, or to generate genetically pure cultures from a mixed culture of genetically different organisms. Several methods are available to plate out cells. One technique is known as "streaking".
The growth of bacteria in laboratory cultures is the mainstay method used by bacteriologists. Both solid and liquid culture media are used. Solid culture medium is usually nutrient agar in a petri dish. The constituents of the nutrient agar vary according to the bacteria under investigation.