Name the group of organisms and the substrate they act on to produce biogas.

Explanation

To answer the question regarding the group of organisms and the substrate they act on to produce biogas, we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Identify the Substrate**:
- The primary substrate used for biogas production is animal dung. This can include cattle dung, which is the most commonly used, as well as human dung.

2. **Identify the Group of Organisms**:
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