Green sulfur bacteria
|Green sulfur bacteria|
|Green sulfur bacteria in a Winogradsky column|
Most green sulfur bacteria are mesophilic. They prefer moderate temperatures, and all of them live in water. They are typical of the bacteria which evolved on the early Earth: they live in anaerobic conditions. They are usually found in the top millimeters of sediment, where there is reduced sulfur. They are capable of photosynthesis in low light conditions.
The Black Sea, an extremely anoxic environment, has a large population of green sulfur bacteria at about 100m depth. The light is poor in this region of the sea: here bacteria get most of their energy from chemical reactions. They need very little energy for cellular maintenance.