State two economically important uses of archaebacteria

Explanation

### Step-by-Step Solution:

1. **Definition of Archaebacteria**: Archaebacteria are a group of prokaryotic microorganisms that are distinct from eubacteria. They are known for their ability to thrive in extreme environments, such as high temperatures, high salinity, or acidic conditions.

2. **Subgroups of Archaebacteria**: Archaebacteria can be categorized into three main subgroups:
- **Methanogens**: These archaebacteria produce methane gas as a byproduct of their metabolic processes.
- **Halophiles**: These organisms thrive in high-salt environments.
- **Thermoacidophiles**: These archaebacteria can survive in extremely hot and acidic conditions.
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