Iron bacterium is

Options

A. Beggiotoa
B. Geobacillus
C. Thiobacillus
D. None of the above.

Answer

To determine what an iron bacterium is, we can analyze the options provided and identify the correct one based on their characteristics.

### Step-by-Step Solution:

1. **Understanding Iron Bacteria**:
- Iron bacteria are microorganisms that obtain energy by oxidizing dissolved ferrous iron (Fe²⁺) to ferric iron (Fe³⁺). This process is crucial for their energy metabolism.

2. **Evaluating the Options**:
- **Option 1: Bagiota**:
- Bagiota is known for oxidizing hydrogen sulfide (H₂S) as its energy source, forming intracellular sulfur droplets. This does not relate to iron oxidation.
- **Option 2: Geobacillus**:
- Geobacillus belongs to the kingdom Bacteria and the phylum Bacillus. However, it is not specifically known for iron oxidation.
- **Option 3: Thiobacillus**:
- Thiobacillus is a gram-negative bacterium that oxidizes thiosulfate and elemental sulfur to sulfate. Importantly, it is also recognized as an iron bacterium or iron-oxidizing bacteria, as it can oxidize dissolved ferrous iron to obtain energy.
- **Option 4: None of the above**:
- This option would only be correct if none of the previous options were valid, which is not the case here.

3. **Conclusion**:
- Based on the characteristics of the options, **Thiobacillus** is the correct answer as it is known as an iron bacterium due to its ability to oxidize ferrous iron.

### Final Answer:
**Thiobacillus** is the correct answer, as it is known as an iron bacterium.

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