Answer:
Growth media are used to grow microorganisms in a lab setting. Some media are liquids; others are more solid or gel-like. A growth medium provides nutrients, including water, various salts, a source of carbon (like glucose), and a source of nitrogen and amino acids (like yeast extract) so microorganisms can grow and reproduce. Ingredients in a growth medium can be modified to grow unique types of microorganisms. For example; <u> </u><u>Nutrient agar </u> is a general-purpose, non-selective growth media, <u> Chocolate agar </u> is a non selective, enriched growth medium with red blood cells that have been lysed by heat, Columbia Nalidixic Acid (CNA) and <u> Mannitol Salt agar </u> are selective agar for Gram positive organisms and <u> </u><u>MacConkey </u>agar is a selective agar for Gram negative organisms, Mannitol salt agar MSA is a commonly used selective and differential growth medium that encourages the growth of bacteria that ferments mannitol, <u> </u><u>Nutrient broth </u> is an example of a liquid that supports growth of a variety of organisms.
Explanation:
Growth media are classified based on their composition as:
1. General Purpose Media: These type of media support the growth of non-fastidious organisms, that do not require special nutrients for growth, and they also serve as a base for certain modified media. An example is the nutrient agar
2. enriched media: these media, like the name implies, is one that has been modified by the addition of special growth factors and nutrients called enrichment. An example is chocolate agar where lysed blood is added to nutrient base agar, when the blood cells are lysed slowly at 80°C, nicotinamide adenine dinucleotide (factor V or NAD) and hemin (factor X), are released into the medium, and these support growth of certain fastidious organisms like <em>Haemophilus influenza </em>bacteria.
3. Selective media: These kinds of media contain substances that support the growth of certain organisms while in turn preventing the growth of others due to the presence of certain inhibitory factors. Examples are: Mannitol Salt Agar, which supports growth of Gram-positive organisms and MacConkey agar, which supports the growth of Gram-positive organisms
4. Non Selective media: These type of media have no biases against the growth of certain organisms, that is, they do not contain certain inhibitory factors that impede the growth of certain organisms.
5. Differential media: These media contain chromogenic agents that change colour and helps to differentiate one organism from the other, making for ease of identification especially for organisms with similar properties.
Finally, a broth is a growth medium that fo not contain agar, hence, it is liquid and not solid.
