Institute of Microbiology, Russian Academy of Science, 60 let Oktyabrya pr., 7a, Moscow 117811, Russia

Abstract

To clarify the role of cyanobacteria in phosphate precipitation a laboratory modelling of this process was carried out with Microcoleus chthonoplastes - the dominant halophilic form of cyanobacteria communities in the lagoons of Ozero Sivash (Sea of Azov). Mineralized filaments and sheaths from hydroxyl- or fluorapatite that were experimentally obtained are morphologically similar to structures discovered in ancient phosphates of Hovsgol Nuur. The investigations of phosphotization process allows to determine some parameters: the rate of phosphorus consumption by cell, the concentration of inorganic phosphorus that is necessary for cell growth and mineralization, threshold concentrations of intercellular phosphorus. Morphological changes of cyanobacteria in the process of mineralization were also studied by electron microscope. It was shown that amount and proportion of intercellular polyphosphates changing together with fluctuations of phosphorus concentration in the environment determined the future mineralization of cyanobacteria - formation of sheaths or mineralization of cells and filaments. The authors suppose that cyanobacteria community played in the past an important role in the formation of phosphorites.