Models for "Early Earth" microbial communities

The lake Alat in Bavaria is one of our model systems for conditions on Early Earth. At 15 m depth below the water surface, oxygen content decreases rapidly, whereas hydrogen sulfide concentration is increasing. Methanotrophic bacteria, other aerobes and algae dominate the oxic zone above this depth, whereas along the transition zone a dense layer of anoxygenic photosynthetic purple sulfur bacteria is dominant. Permanent oxygen deficiency and the presence of H₂S in this lake and in other ponds, springs and geysers serve us as model environments for the chemistry of oceans on Early (anoxic) Earth.

Figure. Lake Alat: Microbial community dominated by purple sulfur bacteria at the oxic/anoxic interface.

 

Reference                                                                                                                                                                                                                             Rincón-Tomás et al., 2016 Intl J Astrobiol. 15: 219-229.