Which of the following organisms is not an obligate aerobe ?

Options

A. Pseudomonas aeruginosa
B. Klebsiella pneumoniae
C. Mycobacterium tuberculosis
D. Bacillus sp

Answer

To determine which of the following organisms is not an obligate aerobe, we need to understand what an obligate aerobe is and analyze the options provided:

1. **Definition of Obligate Aerobe**: An obligate aerobe is an organism that requires oxygen for growth and metabolism. These organisms utilize oxygen in cellular respiration to metabolize substances like sugars and fats to obtain energy. In this process, oxygen acts as the terminal electron acceptor in the electron transport chain.

2. **Analyzing the Options**:
- **Pseudomonas aeruginosa**: This is a well-known obligate aerobe. It requires oxygen for its growth and metabolism.
- **Lapsila pneumoni**: This organism is known to be anaerobic, meaning it does not require oxygen for growth. It is a lactose-fermenting, non-motile, encapsulated gram-negative bacterium found in the normal flora of the mouth, skin, and intestines.
- **Mycobacterium tuberculosis**: This bacterium is also classified as an obligate aerobe. It requires oxygen for its growth and is known for causing tuberculosis.
- **Bacillus species**: Many Bacillus species are obligate aerobes, although some can be facultative anaerobes. However, they generally prefer aerobic conditions.

3. **Conclusion**: Among the options provided, **Lapsila pneumoni** is the only organism that is not an obligate aerobe as it is anaerobic.

Thus, the correct answer is **Lapsila pneumoni** (Option 2).