Journal of Siberian Federal University. Biology / The Role of the Microbial Community in Mineral Formation in the Thermal Springs of the Baikal Region

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Issue
Journal of Siberian Federal University. Biology. 2018 11 (4)
Authors
Budagaeva, Valentina G.; Barkhutova, Darima D.
Contact information
Budagaeva, Valentina G.: Institute of General and Experimental Biology SB RAS 6 Sakhyanova, Ulan-Ude, 670047, Russia; ; Barkhutova, Darima D.: Institute of General and Experimental Biology SB RAS 6 Sakhyanova, Ulan-Ude, 670047, Russia
Keywords
thermal springs; microbial mat; mineral formation; microbial-induced mineralization; diffractogram; silicon dioxide; silica; calcite; aluminosilicates; framboid pyrite
Abstract

Alkaline nitrogen thermal springs characterised by high temperatures and pH values are extreme habitats in the Baikal area. Microbial mats are prokaryotic communities consisting of photosynthetic cyanobacteria and a range of other aerobic and anaerobic microorganisms. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were used to study the composition of minerals formed in microbial communities in the outflows of the Baikal thermal springs. Among the minerals, calcite, quartz and opal were identified. Deposits of iron sulphide (pyrite framboids), a product of the metabolic activity of microorganisms, were found in hydrogen sulphide springs. The calcite crystals had an ellipsoidal, faceted cubic or prismatic shape. Silica (opal) was deposited as a dense crust with silicified filaments of cyanobacteria; siliceous formations of biogenic origin represented by siliceous covers on the filaments of cyanobacteria and diatom frustules were observed. Microbial fouling and mats serve as reaction surfaces for the nucleation of heterogeneous silica particles in the process of amorphous silica and opal formation. Calcite is formed as a result of the metabolic activity of organisms due to the appearance of local zones with high pH values and the formation of a glycocalyx (exopolysaccharides), which absorbs calcium ions. Pyrite framboids grow on the surfaces of fragments of diatom shells, and deposits of individual crystallites are also observed in the thickness or on the surface of microbial mats

Pages
340-355
Paper at repository of SibFU
https://elib.sfu-kras.ru/handle/2311/109186

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