Biogas itself is an intermediate product that produced by biological degradation of the organic matter using bacteria in anaerobic environment.
The decomposition process is divided into four steps (see Table 2).
Each of them is accompanied by different bacteria groups.
The methanogenic bacteria are the main driven for methane production.
There are several types of methanogenic bacteria: methano bacterium, methano bacillus, methanococcus, andnmethanosarcina.
Each of them can grow in a specific environment condition.
If they could not meet the optimal condition, growth may at a lower rate or the bacteria may die, depending on species and conditions