Question

Which of the following is NOT categorized as a cell wall deficient bacteria?

• A. Mycoplasma
• B. Protoplast
• C. Sphaeroplast
• D. Archaebacteria

Hint:

Protoplasts and sphaeroplasts are unstable CWD forms created in the lab, whereas Mycoplasma is the only naturally occurring, stable genus of CWD bacteria.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Cell wall deficient (CWD) bacteria are bacteria that lack a peptidoglycan cell wall, either naturally as part of their biology or artificially due to environmental/chemical treatment.

Step 2: Detailed Explanation:
Let us evaluate each option:
- Mycoplasma: Naturally occurring, stable bacteria that completely lack a cell wall. They are bounded only by a triple-layered cell membrane. Thus, they are cell wall deficient.
- Protoplast: Artificially produced spherical cells derived from Gram-positive bacteria whose peptidoglycan cell wall has been completely removed (usually by lysozyme treatment). Thus, they are cell wall deficient.
- Sphaeroplast: Artificially produced spherical cells derived from Gram-negative bacteria whose peptidoglycan cell wall has been partially removed, leaving the outer membrane intact. Thus, they are cell wall deficient.
- Archaebacteria: A distinct domain of single-celled microorganisms that possess unique, robust cell walls composed of pseudopeptidoglycan, complex glycoproteins, or polysaccharides. They are not cell wall deficient.
Therefore, Archaebacteria are not categorized as cell wall deficient bacteria.

Step 3: Final Answer
The correct option is (D).