Over all the time of their existence cyanobacteria had two quantity peaks: about
two and one billion years ago. Bacterial mats mineral rests (stromatolites) form thick rock massifs. The spring communities with a higher sulfides contain possess a specific feature, i.e. a complex of dominants that could consist of diverse cyanobacteria species (Phormidium spp., Oscillatoria spp, Scytonema sp. and others), bacteria and algae. Here anoxygenic phototrophic bacteria Chloroflexus sp. or hemolitotrophic sulfur-reducing bacteria Thiothrix sp. can be labeled as active agents and edificators of the communities. In non-sulfide springs monodominant communities can be observed. FK506 These communities are represented by cyanobacteria Phormidium spp. or Mastigocladus laminosus, that formed thick gelatinous mats, in contrast to sulfide springs where mats were thin and easily destructible. In cyanobacterial mats the precipitating of amorphous SiO2 and calcite has been determined. SiO2 depositions mainly occur Selleckchem Venetoclax as the result of the solution thermodynamic parameters changes. Calcite formation in a cyanobacterial mat looks like isometric (10–30 μm) crystals. There was found a direct relation between calcium contain in solution and calcite forming in mats. Microbial mats decisive role in large amount of elements accumulation has been determined. These
elements are distributed in different ways between organic and mineral substance of the microbial
mats. The distribution of K, Mn, Ni, Cu, Zn, Fe is regular, Ca, Rb, Sr are almost totally related with the mats mineral part, while Ga, Ge Astemizole and Br are accumulated in mats organic substance. The microbial mats destruction does not entail Ga, Ge and Br transformation into minerals, but results in their being carried away by water streams. Almost all the elements studied are accumulated by microbial communities. Exclusively in non-sulfide springs (Garga and Uro) Ge is accumulated by cyanobacterial mats. Thus, basing upon studying of structure and some specific features of Baikal rift zone hydrotermes microbial communities functioning, it is possible to get a notion about the processes which occurred in Precambrian primary prokaryotic community and its significance for the modern biosphere formation. This work was supported by the RFBR (06-05-64767, 06-05-64957, 08-05-00968); IP: 18-16 and 96; SS-5736.2008.5; RPN.2.1.1.702, PP SB RAS [2116]24 and Program “BOE”. Gerasimenko L.M., Orleansky V.K. (2004) Actualistic paleontology of cyanobacteria. In the same book: 80–108. Zavarzin G.A. (2004) Development of microbial communities in the Earth’s history. Ed. by V.F Galchenko, Proceedings of Winogradsky Institute of Microbiology XII: 149–159. Moscow, Nauka. E-mail: bal412003@mail.