Boreskov

OP‐28ROLE OF CYANOBACTERIA FROM DIFFERENT ENVIRONMENTSIN FORMATION OF SEDIMENTORY ROCKSGerasimenko L.*, Orleansky V.*, Samylina O.*, Zaitseva L.**, Ushatinskaya G.***Winogradsky Institute of Microbiology, RAS,pr. 60‐letiya Oktyabrya 7/2, Moscow, 117312 Russia**Borissiak Paleontological Institute, RAS, ul. Profsoyuznaya 123, Moscow, 117321 RussiaCyanobacteria have been recognized as key players in the precipitation, formation andtransformation of some minerals (phosphates, carbonates, siliceous and clay minerals).These bacteria produce extracellular polysaccharides (EPS), which act as binding sites foranions and cations. Also they are able to increase pH of environment as a result ofphotosynthetic activity. Both processes contribute to precipitation of sedimentary rocks andinfluence on morphology and mineralogy of sediments (Dittrich, Sibler, 2011).To study processes of phosphatization, carbonatization and siliciphication in laboratorywere used a variety of cyanobacteria, such as halophilic strain of Microcoleuschthonoplastes, alkaliphilic Phormidium sp. and ‘Euhalothece natronophila’, thermophilicOscillatoria terebriformis and Mastigocladus laminosus. These species of cyanobacteria areusual enough and spread worldwide in their ecological niches, so we can judge aboutuniversal mechanisms. The results of our laboratory experiments were related to fieldobservations.To study process of phosphatization we conducted comparative analysis of fieldobservations of Khubsugul phosphorites (Mongolia) with results of laboratory experimentsusing halophilic cyanobacterium Microcoleus chthonoplastes. It was demonstrated thatformation of phosphorite was connected with replacing of cyanobacterial trichomes bycalcium phosphate. This process elapsed with rapid speed (first hours, days) and may beassociated with the change of seasons or with a significant shallowing of the basin(Gerasimenko et al., 1998). Laboratory fossils were similar to fossils from Khubsugulphosphorites.A role of alkaliphilic cyanobacterium Phormidium sp. in carbonate mineralization wasstudied in model experiments in laboratory. Carbonate precipitation can occur when seawater enriched with Ca +2 and Mg +2 mixes with continental water enriched with sodiumcarbonate. In particular, the relationship between chemical composition of the environmentand precipitation of carbonates was studied. Our observations show that formation of77