Question

multiple select question
select all that apply
which of the following are retention agents used in microbiological media? more than one answer may be correct.

□ antibiotics
□ methylene blue
□ india ink
□ eosin

(3) need help? review these concept resources.

bale your confidence to submit your answer: | next | review | clear |

Explanation:

In microbiological media, selective agents are used to inhibit the growth of unwanted microbes and promote the growth of desired ones.

• Bile salts: They are commonly used in media (like MacConkey agar) to inhibit the growth of gram - positive bacteria, thus acting as a selective agent for gram - negative enteric bacteria.
• Crystal violet: It is used to inhibit the growth of gram - positive bacteria in some media (e.g., MacConkey agar also has crystal violet for this purpose), so it is a selective agent.
• Brilliant green: It is used in media (such as Salmonella - Shigella agar) to inhibit the growth of many gram - positive and some gram - negative bacteria, acting as a selective agent.
• Eosin Y (Eosin yellowish): It is part of differential media (like Eosin - Methylene Blue agar) but also has a selective effect against gram - positive bacteria.

Answer:

A. Bile salts, B. Brilliant green, C. Eosin Y (Eosin yellowish), D. Crystal violet (assuming the options are labeled A - D as Bile salts, Brilliant green, Eosin Y, Crystal violet respectively)