Select the incorrect statement w.r.t methanogens.

Options

A. They are Gram negative
B. Obligate anaerobes
C. Chemoheterotrophs
D. Produce methane gas from `CO_(2)`

Answer

To determine the incorrect statement regarding methanogens, let's analyze each option step by step:

1. **Understanding Methanogens**: Methanogens are a specific group of microorganisms, primarily archaea, that produce methane as a metabolic byproduct in anaerobic conditions. They are commonly found in environments like the intestines of ruminants.

2. **Analyzing the Options**:
- **Option 1: They are gram negative**. This statement is incorrect. Methanogens are typically classified as gram-positive bacteria.
- **Option 2: They are obligate anaerobic**. This statement is correct. Methanogens thrive in environments devoid of oxygen.
- **Option 3: They are chemoheterotrophs**. This statement is also correct. Methanogens utilize organic compounds for energy and carbon.
- **Option 4: They produce methane gas from CO2**. This statement is correct as well. Methanogens convert carbon dioxide and hydrogen into methane.

3. **Conclusion**: Based on the analysis, the incorrect statement is **Option 1: They are gram negative**.