Question

Acinetobacter radioresistens is a ____.

• A. Gram‐negative spiral bacterium
• B. Gram‐ positive cocci
• C. Gram‐positive coccobacillary rod
• D. Gram‐negative coccobacillary rod

Hint:

Acinetobacter is often confused under the microscope because it looks like "Round Rods" (Coccobacilli). Just remember: Genus Acinetobacter = Gram-Negative Coccobacilli.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks for the Gram-staining reaction and morphological shape of Acinetobacter radioresistens, a bacterium known for its extreme resistance to ionizing radiation.

Step 2: Detailed Explanation:

• Genus Acinetobacter: Members of this genus are typically found in soil and water. They are known for being strictly aerobic and non-fermentative.

• Staining Property: All Acinetobacter species are Gram-negative. However, they are sometimes difficult to decolorize and can falsely appear Gram-positive in old cultures.

• Morphology: They are coccobacilli (intermediate between a sphere/coccus and a rod/bacillus). In the stationary phase of growth, they appear primarily as cocci, but they are technically classified as coccobacillary rods.

• A. radioresistens: This specific species is highly resistant to gamma radiation, making it an organism of interest in food irradiation studies and astrobiology. Like others in its genus, it is a Gram-negative coccobacillary rod.

Step 3: Final Answer:
Acinetobacter radioresistens is a Gram-negative coccobacillary rod.