Which of the following bacteria uses H2S as H+ donor for its nutrition.

Options

A. Chromatium
B. Thiospirillum
C. Chlorobium
D. Chloronema

Answer

To solve the question, "Which of the following bacteria uses H2S as H+ donor for its nutrition?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Bacteria**:
- Bacteria can be classified based on their nutritional modes into autotrophic and heterotrophic. Autotrophic bacteria can further be divided into photosynthetic and chemosynthetic bacteria.

2. **Identify Photosynthetic Bacteria**:
- Photosynthetic bacteria can use different hydrogen donors. In oxygenic photosynthesis (like in green plants), water (H2O) is used as the hydrogen donor, resulting in the release of oxygen. In contrast, some bacteria use hydrogen sulfide (H2S) instead of water.

3. **Recognize Sulfur Bacteria**:
- Sulfur bacteria, such as *Thiospirillum*, utilize H2S as a hydrogen donor. This process is known as anoxygenic photosynthesis, where no oxygen is produced, but instead, sulfur is precipitated.

4. **Evaluate the Options**:
- The question likely provides multiple options. Among them, identify which one is a sulfur bacterium. The example given in the transcript is *Thiospirillum*, which is known for using H2S.

5. **Eliminate Incorrect Options**:
- The other options mentioned, such as Comacium, Chlorobium, and Chloronema, are not sulfur bacteria and typically perform oxygenic photosynthesis using water as a hydrogen donor.

6. **Conclude the Answer**:
- Based on the information gathered, the correct answer to the question is *Thiospirillum*, which is the bacterium that uses H2S as an H+ donor for its nutrition.

### Final Answer:
The bacterium that uses H2S as an H+ donor for its nutrition is *Thiospirillum*.