Due to the exciting discovery of methane gas on Mars, the types of bacteria that scientists will be looking for there are known as METHANOGENS.
Here’s what Wikipedia says about this kind of bacteria:
Methanogens are archaea that produce methane as a metabolic byproduct in anoxic conditions. They are common in wetlands, where they are responsible for marsh gas, and in the guts of animals such as ruminants and humans, where they are responsible for the methane content of flatulence. In marine sediments biomethanation is generally confined to where sulfates are depleted, below the top layers. Others are extremophiles, found in environments such as hot springs and submarine hydrothermal vents as well as in the “solid” rock of the earth’s crust, kilometers below the surface.
And here’s what the little Martians probably look like:
What will they say when they meet us for the first time?
“Take us to your lower intestine!”
[Image source: here]