Final answer:
Gram-negative broth (GN) functions as an enrichment media, which is used to foster the growth of specific bacteria, increasing their numbers for detection. It is different from selective media that inhibit unwanted microbes or differential media that distinguish between microbial types.
Step-by-step explanation:
The purpose of Gram-negative broth (GN) is its role as an enrichment media. This type of culture medium is designed to increase the numbers of a desired organism to detectable levels. Enrichment media are essential for cultivating bacteria that may be present in low numbers or are overgrown by other bacteria present in the sample. Selective and differential media are different; they have other specific roles in bacterial culture. Selective media support the growth of specific microorganisms while inhibiting the growth of others, and differential media are used to distinguish between different types of bacteria based on certain biochemical reactions that change the media's appearance.