Methanogens in a freshwater pond

All methanogens belong to the domain Archaea and are strict anaerobes. They are called methanogens because they degrade organic matter to methane by feeding on those components. They thrive in a large variety of habitats among which are anoxic sediments of freshwater lakes. As methanogens grow quite slowly a lot of patience is needed to cultivate them in the lab.

The Flötenteich, a small freshwater pond in Oldenburg, Germany, on a cold day in April (air temperature: 11°C, water temperature: 8°C).