What are selective media used for in bacteriology?

Selective media are specifically designed to favor the growth of certain types of bacteria while suppressing the growth of others. This is achieved through the inclusion of specific nutrients, inhibitors, or indicators that create an environment conducive for the targeted bacteria. For example, a selective medium may contain a high concentration of salt to encourage the growth of salt-tolerant bacteria like Staphylococcus, while inhibiting the growth of non-tolerant organisms.

By isolating particular bacteria from mixed cultures, selective media play a crucial role in identifying and studying specific strains, making it easier to understand their unique characteristics, metabolic capabilities, and pathogenicity. This approach is essential in clinical diagnostics, environmental studies, and research applications where specific bacterial populations are of interest.

The other options do not describe the primary function of selective media effectively. Promoting the growth of all bacteria equally would defeat the purpose of using selective media, while eliminating all bacteria in a sample and enhancing photosynthetic activity are not relevant to the selective growth goals inherent to these types of media.