what is selective a medium in microbiology
MacConkey agar is a selective medium containing bile salts and crystal violet that inhibits the growth of Gram-positive bacteria while allowing for the growth of Gram-negative bacteria.MacConkey agar is often used when investigating and culturing fecal bacteria.he MacConkey agar we talked about as an example of a selective media is also a differential media. In addition to the selective bile salts and crystal violet, MacConkey agar contains a pH indicator and the sugar lactose.