What is the function of a selective medium in microbiology?

What is the function of a selective medium in microbiology?

• A. To increase the growth rate of all bacteria
• B. To favor particular bacteria while inhibiting others
• C. To detect biochemical reactions in bacteria
• D. To support anaerobic bacteria growth only

Answer: (B)

A selective medium in microbiology is designed to favor the growth of particular bacteria while inhibiting the growth of others. This is achieved through the inclusion of specific substances in the medium that either promote the growth of the intended microorganisms or suppress undesired ones. For instance, a selective medium can be formulated with certain antibiotics or salts that only specific bacteria can tolerate, allowing for the isolation of these target organisms from a mixed population. The use of selective media is crucial in identifying and studying particular microbes, especially in clinical and environmental samples. By creating conditions that favor certain bacteria, researchers can obtain a clearer picture of the microbial community or isolate pathogenic organisms. In contrast, the other options do not accurately describe the primary function of a selective medium. For example, increasing the growth rate of all bacteria would defeat the purpose of selection, as it would not isolate specific organisms. Detecting biochemical reactions pertains more to differential media—where different bacteria show distinct appearances based on their metabolic processes—while supporting only anaerobic bacteria’s growth is a more specific function that does not represent the broader purpose of selective media.

A selective medium in microbiology is designed to favor the growth of particular bacteria while inhibiting the growth of others. This is achieved through the inclusion of specific substances in the medium that either promote the growth of the intended microorganisms or suppress undesired ones. For instance, a selective medium can be formulated with certain antibiotics or salts that only specific bacteria can tolerate, allowing for the isolation of these target organisms from a mixed population.

The use of selective media is crucial in identifying and studying particular microbes, especially in clinical and environmental samples. By creating conditions that favor certain bacteria, researchers can obtain a clearer picture of the microbial community or isolate pathogenic organisms.

In contrast, the other options do not accurately describe the primary function of a selective medium. For example, increasing the growth rate of all bacteria would defeat the purpose of selection, as it would not isolate specific organisms. Detecting biochemical reactions pertains more to differential media—where different bacteria show distinct appearances based on their metabolic processes—while supporting only anaerobic bacteria’s growth is a more specific function that does not represent the broader purpose of selective media.