Final answer:
A differential media allows differentiation of microorganisms based on the appearance and chemical reactions, such as changes in color in response to specific metabolic activities. Selective media inhibit certain microbes while supporting others, while enriched media add essential growth nutrients.
Step-by-step explanation:
A culture medium that distinguishes between groups of microorganisms based on differences in appearance due to various chemical reactions is known as differential media. These media exploit the different metabolic activities of organisms, such as enzyme production, to reveal changes in the medium or colony color. For example, on MacConkey agar, lactose fermenters produce an acid that turns the medium and colonies hot pink, facilitated by the pH indicator neutral red.
In addition to differential media, there are selective media that favor the growth of certain microorganisms while inhibiting others, and enriched media which contain nutrients essential for the growth of specific organisms. Culture media is crucial for the growth and maintenance of cells in vitro, providing necessary nutrients, hormones, and support systems such as agar, which offers a solid growth surface.