For isolating bacteria from various types of specimen.MacConkey agar, chocolate agar, nutrient agar, blood agar, etc., are some examples of solid culture media. Solid medium has a physical structure and allows bacteria to grow in physically informative or useful ways (e.g., as colonies or in streaks). Solid culture media contain agar at a concentration of 1.5-2.0% or some other primarily inert solidifying agent. The percentage of agar used determines the consistency of the medium. Uses of Culture Media Based on ConsistencyĬulture media are divided into three types solid medium, semi-solid medium, and liquid medium, based on consistency.Mycobacterium leprae, Rickettsia, Chlamydia trachomatis, and Treponema pallidum are obligate intracellular parasites. Organisms that cannot grow in the artificial culture medium are obligate parasites. Bacterial culture media can be classified based on composition, consistency, and purpose.Īll microorganisms cannot grow in a single culture medium many can’t grow in any known culture medium. If a culture medium meets a bacterial cell’s growth requirements, then that cell will multiply to sufficient numbers to allow visualization by the unaided eye. For culturing many microorganisms, this information is not essential either.Ĭulture media contains nutrients and physical growth parameters necessary for microbial growth. Casein (milk protein), beef (beef extract), soybeans (tryptic soy broth), yeast cells (yeast extract), or any other highly nutritious yet impure substances are used to prepare complex media thus, the exact composition of the medium is not known. Therefore, the exact composition of a defined medium is known.Ĭomplex media are prepared using digests of microbial, animal, or plant products. Defined media are prepared by adding precise amounts of highly purified inorganic or organic chemicals to distilled water. Defined media and complex media are two broad classes of culture media used in microbiology.
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