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Introduction. To date, pipeline transport is an important, highly efficient and promising method of transporting water, gas, oil, etc. It is often necessary to overcome water barriers in the course of laying pipelines. At the design stage, many engineering problems can be solved by analyzing the velocity distribution and evaluating hydraulic resistances. The value of hydraulic resistances depends on the position of the pipeline crossing relative to the incoming flow. Materials and methods. Experimental studies of models of pipeline crossings in a wind tunnel were conducted to determine the values of coefficients of hydrodynamic resistance and the lifting force. Results. During the experiments, components of the flow force, acting on the pipeline crossing, were measured using the strain gauge balance at different Reynolds numbers applied to find values of coefficients of hydrodynamic resistance and the lifting force for a pipeline lying on a screen at different angles to the incoming flow. 1/2 and 1/3 of the pipeline diameter was buried in the riverbed and safeguarded by flexible concrete mats. Conclusions. The lowest values of coefficients of hydrodynamic resistance and the lifting force were obtained for a pipeline with 1/2 of the pipeline diameter buried in the riverbed and laid perpendicularly to the flow direction. Concrete mats are the optimal loading for non-buried pipelines.

Data indicating the important role of microorganisms in the redistribution of REEs in the weathering crust and the decisive role in the concentration of REEs during the formation of ores in the upper ore horizon of the Tomtor field are obtained. The uptake of REEs was carried out by the community of microorganisms, such as phototrophs, methanogens, methanotrophs, and proteobacteria, which form the basis of the microbiocenosis for this paleoecosystem. The isotopic composition of C carbonates in all samples studied with fossilized microorganisms corresponds to the biogenic one, and the isotopic composition δ18ОSMOW (from 7 to 20‰) indicates the endogenous (hydrothermal) and, to a lesser extent, exogenous nature of the solutions. The low (87Sr/86Sr)I values of carbonates (~0.7036–0.7042) exclude the participation of seawater.

In the south of western Siberia (Russia), there are many unique and unexplored soda, saline, and freshwater lakes. In this study, the results are presented on microbial diversity, its metabolic potential, and their relation with a set of geochemical parameters for a hypersaline lake ecosystem in the Novosibirsk region (Oblast). The metagenomic approach used in this work allowed us to determine the composition and structure of a floating microbial community, the upper layer of silt, and the strata of bottom sediments in a natural saline lake via two bioinformatic approaches, whose results are in good agreement with each other. In the floating microbial community and in the upper layers of the bottom sediment, bacteria of the Proteobacteria (Gammaproteobacteria), Cyanobacteria, and Bacteroidetes phyla were found to predominate. The lower layers were dominated by Proteobacteria (mainly Deltaproteobacteria), Gemmatimonadetes, Firmicutes, and Archaea. Metabolic pathways were reconstructed to investigate the metabolic potential of the microbial communities and other hypothetical roles of the microbial communities in the biogeochemical cycle. Relations between different taxa of microorganisms were identified, as was their potential role in biogeochemical transformations of C, N, and S in a comparative structural analysis that included various ecological niches.

Mars is considered to be one of the most favourable places in the Solar System to search for past and present life. In the past Mars was warmer and wetter, so terrestrial halophiles can be regarded as analogues of hypothetical ancient Martian halophiles. In this study we used microorganisms from unique Altai region (Russia) to estimate the capability of terrestrial bacteria and archaea to survive at low temperatures and high concentration of salts and metals, similar to the Martian environment. The current report demonstrates that both halophilic archaea and halotolerant bacteria from saline lakes of the Altai region may be considered as analogues of ancient Martian organisms, since they are able to withstand conditions that hypothetically existed in subsurface layers of the early Mars (low temperatures, salt solutions with a high content of NaCl) with only slight decrease in viability. We also found that the studied microorganisms can use some organic substances found in meteorites. We consider that transfer of unicellular halophiles from Earth to Mars was possible, and, moreover, they could successfully survive and grow on early Mars. Adjusting our growth media to the chemical composition of the lakes, from which the studied strains were isolated, resulted in significant increase in survival and growth rates. Certain strains could survive several freeze–thaw cycles at −70 °C typical for Martian nights.

The article describes and gives the results of laboratory hydraulic investigations to determine the kinematic characteristics of a flow interacting with flexible concrete protective coatings on the bottom of a watercourse. The laboratory equipment used in conducting the experiments is described. The schemes of the hydraulic tests and the results of measurements by two types of protective coatings differing in configuration of the blocks are given. The increase in the flow rate in the gaps between the blocks of the protective mats in the bottom region and decrease in the rate in the part of the flow above the protective coating are recorded.

In this study we demonstrated that exposure of Escherichia coli (E. coli) to terahertz (THz) radiation resulted in a change in the activities of the tdcABCDEFGR and matA–F genes (signs of cell aggregation), gene yjjQ (signs of suppression of cell motility), dicABCF, FtsZ, and minCDE genes (signs of suppression of cell division), sfmACDHF genes (signs of adhesin synthesis), yjbEFGH and gfcA genes (signs of cell envelope stabilization). Moreover, THz radiation induced E. coli csg operon genes of amyloid biosynthesis. Electron microscopy revealed that the irradiated bacteria underwent increased aggregation; 20% of them formed bundle-like structures consisting of two to four pili clumped together. This could be the result of changes in the adhesive properties of the pili. We also found aberrations in cell wall structure in the middle part of the bacterial cell; these aberrations impaired the cell at the initial stages of division and resulted in accumulation of long rod-like cells. Overall, THz radiation was shown to have adverse effects on bacterial populations resulting in cells with abnormal morphology.

For accurate species-level identification of microorganisms, researchers today increasingly use a combination of standard microbiological cultivation and visual observation methods with molecular biological and genetic techniques that help distinguish between species and strains of microorganisms at the level of DNA or RNA molecules. The aim of this work was to identify microorganisms from the ICG SB RAS Collection using an integrated approach that involves a combination of various phenotypic and genotypic characteristics. Key molecular-genetic and phenotypic characteristics were determined for 93 microbial strains from the ICG SB RAS Collection. The strains were characterized by means of morphological, physiological, moleculargenetic, and mass-spectrometric parameters. Specific features of the growth of the strains on different media were determined, and cell morphology was evaluated. The strains were tested for the ability to utilize various substrates. The strains studied were found to significantly differ in their biochemical characteristics. Physiological characteristics of the strains from the collection were identified too, e.g., the relationship with oxygen, type of nutrition, suitable temperature and pH ranges, and NaCl tolerance. In this work, the microorganisms analyzed were combined into separate groups based on the similarities of their phenotypic characteristics. This categorization, after further refinement and expansion of the spectrum of taxa and their metabolic maps, may serve as the basis for the creation of an "artificial" classification that can be used as a key for simplified and quicker identification and recognition of microorganisms within both the ICG SB RAS Collection and other collections.Для точной видовой идентификации микроорганизмов сегодня все чаще применяют сочетание стандартных микробиологических методов культивирования и визуального наблюдения с методами молекулярной биологии и генетики, помогающими различать виды и штаммы микроорганизмов на уровне молекул ДНК или РНК. Целью данной работы было проведение идентификации микроорганизмов из Коллекции ИЦиГ СО РАН с помощью комплексного подхода, сочетающего использование широкого спектра фенотипических и генотипических признаков. Для 93 штаммов микроорганизмов Коллекции ИЦиГ СО РАН описаны ключевые молекулярно-генетические и фенотипические свойства. Рассмотрены морфологические, физиологические, молекулярно-генетические и масс-спектрометрические характеристики штаммов. Установлены особенности роста штаммов на разных средах, изучена морфология клеток. Штаммы протестированы на способность использовать различные субстраты. Обнаружено, что исследованные штаммы значительно различались по своим биохимическим признакам. Определены физиологические особенности штаммов коллекции: отношение к кислороду, тип питания, диапазон температур и рН, отношение к NaCl и др. Исследованные микроорганизмы объединены в отдельные группы на основании сходства их фенотипических характеристик, что может при дальнейшей доработке и расширении спектра таксонов и их метаболических карт послужить основой для создания «искусственной» классификации, которая может быть использована в качестве ключа для упрощенной и более быстрой идентификации и распознавания микроорганизмов в рамках как Коллекции ИЦиГ СО РАН, так и других коллекций.

Background The Uzon Caldera is one of the places on our planet with unique geological, ecological, and microbiological characteristics. Uzon oil is the youngest on Earth. Uzon oil has unique composition, with low proportion of heavy fractions and relatively high content of saturated hydrocarbons. Microbial communities of the «oil site» have a diverse composition and live at high temperatures (up to 97 °C), significant oscillations of Eh and pH, and high content of sulfur, sulfides, arsenic, antimony, and mercury in water and rocks. Results The study analyzed the composition, structure and unique genetics characteristics of the microbial communities of the oil site, analyzed the metabolic pathways in the communities. Metabolic pathways of hydrocarbon degradation by microorganisms have been found. The study found statistically significant relationships between geochemical parameters, taxonomic composition and the completeness of metabolic pathways. It was demonstrated that geochemical parameters determine the structure and metabolic potential of microbial communities. Conclusions There were statistically significant relationships between geochemical parameters, taxonomic composition, and the completeness of metabolic pathways. It was demonstrated that geochemical parameters define the structure and metabolic potential of microbial communities. Metabolic pathways of hydrocarbon oxidation was found to prevail in the studied communities, which corroborates the hypothesis on abiogenic synthesis of Uzon hydrothermal petroleum.

A comprehensive research of water and cyanobacterial mats in Mogoysky and Shurindinsky thermal springs (Baikal rift zone) was carried out by hydrochemical, chemical, microbiological, and mineralogical methods. Detailed descriptions of the springs location and their characteristics were given. According to their chemical composition, the springs were classified as fluoride-bicarbonate (Mogoysky) and bicarbonatesulfate (Shurindinsky) types with a high concentration of fluorine. This is explained by the interaction of infiltration waters with embedding rocks. A wide diversity of cyanobacteria (14 species of 7 genera) was revealed in the investigated springs. The development of cyanobacteria in microbial mats was observed at water outflows at the temperatures of 37.8 to 76.6°C. Chlorophyll a was the predominant pigment in microbial mats of the studied springs, indicating predominance of cyanobacteria in the mat. Deposition of various pyrite forms, celestite (SrSO4), fluorite (CaF2), calcium carbonate, elemental sulfur, barite, and amorphous silica was found in microbial mats.

Interaction between water flow and ridge bedforms has been studied. The results of experimental studies of velocity distribution over ridge bedforms in a hydraulic laboratory flume are given. The distribution of pressure along the contour of a rigid model ridge, determined in an aerodynamic canal, is also given.

Differential proteomic analysis of the total E.coli protein after exposure to terahertz (THz) radiation was performed. Glutamine synthetase was one of the proteins overexpressed in response to THz radiation. E.coli/pGlnA-GFP biosensor based on the promoter of the glnA gene and the GFP protein was constructed and there was demonstrated that it could detect THz radiation. Such a method of design of biosensors which includes cell irradiation, omics analysis of differential expression of genes, the definition of the most pronounced gene can be used for any region of the electromagnetic spectrum.

The Halomonas sp. isolate SL48-SHIP-3 genome was obtained from metagenomics sequencing of the microbial mat of Salt Lake Number 48 (54.201806N, 78.179194E; Novosibirsk region, Russia). The sequenced and annotated genome is 2,575,909 bp and encodes 2,368 genes.

The Halomonas sp. isolate SL48-SHIP-3 genome was obtained from metagenomics sequencing of the microbial mat of Salt Lake Number 48 (54.201806N, 78.179194E; Novosibirsk region, Russia). The sequenced and annotated genome is 2,575,909 bp and encodes 2,368 genes.

The Phormidium sp. strain SL48-SHIP genome was obtained from metagenomics sequencing of the microbial mat of Salt Lake No. 48 (54.201806 N, 78.179194 E; Novosibirsk Region, Russia). The sequenced and annotated genome is 4,384,607 bp and encodes 3,807 genes.

Halorubrum sp. strain 48-1-W was isolated from a water sample from a saline lake (Novosibirsk Region, Russia, 54°14′N 78°13′E).

Halorubrum sp. strain 48-1-W was isolated from a water sample from a saline lake (Novosibirsk Region, Russia, 54°14′N 78°13′E)., Halorubrum sp. strain 48-1-W was isolated from a water sample from a saline lake (Novosibirsk Region, Russia, 54°14′N 78°13′E). The sequenced and annotated genome is 3,584,929 bp and contains 3,506 genes.

This study is focused on the theoretical issues of biological oxidation of oil hydrocarbons varying from alkanes to polycyclic aromatic hydrocarbons. The biochemical mechanisms of the decomposition of the oil components are shown, as well as the review of data represented in the conventional data bases. The results of the microbial community studies, inhabiting the natural oil seeps of the Uzon caldera, are described in detail. It is the first study of the ecophysiological characteristics of oil-degrading microorganisms isolated from the thermal oil seeps of the caldera.

The Tomtor massif of Paleozoic ultramafic alkaline rocks and carbonatites is located in the northern part of the Sakha Republic (Yakutia). The massif (its total area is ~ 250 km2) is ~20 km in diameter, with a rounded shape and a concentrically zoned structure. The core of the massif consists of carbonatites surrounded by a discontinuous ring of ultramafic rocks and foidolites. The outer part is composed of alkali and nepheline syenites. All rocks are weathered and covered with eluvium, which is the thickest after carbonatites enriched in phosphates and REE. The weathering profile consists of four layers, from the top: kaolinite–crandallite, siderite, goethite, and francolite. The highest-grade ores are observed in the bedded deposit which fills depressions in “sagging” eluvium. The ores are laminated and cryptogranular, with high Nb, Y, Sc, and REE contents (on average, 4.5% Nb2O5, 7–10% REE2O3, 0.75% Y2O3, and 0.06% Sc2O3). The highest-grade ores are natural Nb and REE concentrates. The total REE content in some layers is > 10%. The morphologic features of the highest-grade phosphate ores from the northern part of the Burannyi site were studied. The ore-forming minerals belong to the pyrochlore group, crandallite group (goyazite), and monazite-Ce. The pyrochlore group minerals occur mainly as crystals that were completely replaced by barium–strontium pyrochlore and/or plumbopyrochlore but retained the original faces; also, they occur as numerous conchoidal fragments. The grains of the pyrochlore group minerals sometimes have a zonal structure, with an unaltered pyrochlore core and a reaction rim. Goyazite occurs predominantly as colloform grains. According to SEM and TEM data, monazite occurs in the ores as ~50 nm particles, which cover the outer part of halloysite tubes (800–3000 nm long and 300 nm in diameter) as a dense layer and make up peculiar biomorphic aggregates. The mineralogical data, the occurrence of biomorphic aggregates, and the close association of organic remains with ore minerals suggest that the high-grade ores of the Tomtor deposit, including the Burannyi site, resulted from a hydrothermal–sedimentary process with a presumably important role of bioaccumulation of REE phosphates.

A Gram-reaction-positive, motile, thermophilic spore-forming strain, G1w1T, was isolated from a hot spring of the Valley of Geysers, Kamchatka (Russia). Based on data from the present polyphasic taxonomic study, including phylogenetic analysis of 16S rRNA and spo0A gene sequences, the strain is considered to represent a novel species of the genus Geobacillus , for which the name Geobacillus icigianus sp. nov. is proposed. The type strain is G1w1T ( = VKM B-2853T = DSM 28325T).

The Bacillus altitudinis strain KL4 was isolated from bottom sediments in Lake Krotovaya Lyaga (Novosibirsk Region, Russia, 53.7°N, 77.9°E). The sequenced and annotated genome is 3,738,419 bp long and carries 3,909 genes.

Bacillus altitudinis strain KU-skv2(2) was isolated from a microbial mat on an anthropogenic pipe from Caldera Uzon (Kamchatka, Russia, 54°30′0.23″N, 160°0′15.18″E). The sequenced and annotated genome is 3,739,340 bp in size and encodes 3,929 genes.

This study used geological, geochemical, and microbiological data to examine the Uzon oils and conditions within the Uzon caldera. The trace-element compositions of crude oils and solutions from boreholes and hydrothermal springs were determined by ICP-MS. The majority of hydrothermal manifestations within the Uzon caldera are controlled by three trends of faults. The major fault zone, trending nearly E–W, is located between Kikhpinych and Taunshits volcanoes. It acts as a magma conduit and hosts numerous oval-shaped hydrothermal vents. The Oil site is situated on the periphery of the hottest area of highest hydrothermal activity within the Eastern thermal field. On the Eh–pH diagram, most solutions of the Uzon caldera define distinct fields and trends which correlate with the stability fields for sulfur and iron. The Oil site is characterized by very wide variations in temperature and Eh–pH parameters of pore solutions. The geochemical signatures of the solutions at this site are broadly similar to those from other areas of the Uzon caldera, but differ in their sulfide ion and sulfate ion concentrations. These differences can be explained by mixing of deep chloride-sodium hydrothermal solutions and solutions produced during surface oxidation of sulfide-containing material. With respect to the average continental crust, the Uzon oil is enriched in S, As, and Hg. The crude oil and solutions have broadly similar concentrations of B, S, Cl, As, Se, Br, Cd, I, Hg, and Pb and highly variable concentrations of Ti, V, Cr, Co, Ni, Cu, Cd, Nb, and Sn. The community structure of archaeal assemblages in springs and test pits at the Eastern thermal field was analyzed by 16S rRNA library and pyrosequencing methods. It was found that the proportion of archaea in the microbial communities of the Uzon caldera ranges from 2 to over 70% of the total sequences identified. Crenarchaeota were found in large proportions in all samples except one. The majority of the sequences in four samples were affiliated with Euryarchaeota, which comprise methanogenic archaea, extreme halophiles, and some extreme thermophiles. The results of geological, mineralogical-geochemical, microbiological and physicochemical studies of oil seeps in the Uzon caldera reveal distinctive geochemical characteristics of crude oil and the complexity of oil formation.

Background Microbial mats are a good model system for ecological and evolutionary analysis of microbial communities. There are more than 20 alkaline hot springs on the banks of the Barguzin river inflows. Water temperature reaches 75 °C and pH is usually 8.0–9.0. The formation of microbial mats is observed in all hot springs. Microbial communities of hot springs of the Baikal rift zone are poorly studied. Garga is the biggest hot spring in this area. Results In this study, we investigated bacterial and archaeal diversity of the Garga hot spring (Baikal rift zone, Russia) using 16S rRNA metagenomic sequencing. We studied two types of microbial communities: (i) small white biofilms on rocks in the points with the highest temperature (75 °C) and (ii) continuous thick phototrophic microbial mats observed at temperatures below 70 °C. Archaea (mainly Crenarchaeota; 19.8% of the total sequences) were detected only in the small biofilms. The high abundance of Archaea in the sample from hot springs of the Baikal rift zone supplemented our knowledge of the distribution of Archaea. Most archaeal sequences had low similarity to known Archaea. In the microbial mats, primary products were formed by cyanobacteria of the genus Leptolyngbya. Heterotrophic microorganisms were mostly represented by Actinobacteria and Proteobacteria in all studied samples of the microbial mats. Planctomycetes, Chloroflexi, and Chlorobi were abundant in the middle layer of the microbial mats, while heterotrophic microorganisms represented mostly by Firmicutes (Clostridia, strict anaerobes) dominated in the bottom part. Besides prokaryotes, we detect some species of Algae with help of detection their chloroplasts 16 s rRNA. Conclusions High abundance of Archaea in samples from hot springs of the Baikal rift zone supplemented our knowledge of the distribution of Archaea. Most archaeal sequences had low similarity to known Archaea. Metagenomic analysis of microbial communities of the microbial mat of Garga hot spring showed that the three studied points sampled at 70 °C, 55 °C, and 45 °C had similar species composition. Cyanobacteria of the genus Leptolyngbya dominated in the upper layer of the microbial mat. Chloroflexi and Chlorobi were less abundant and were mostly observed in the middle part of the microbial mat. We detected domains of heterotrophic organisms in high abundance (Proteobacteria, Firmicutes, Verrucomicrobia, Planctomicetes, Bacteroidetes, Actinobacteria, Thermi), according to metabolic properties of known relatives, which can form complete cycles of carbon, sulphur, and nitrogen in the microbial mat. The studied microbial mats evolved in early stages of biosphere formation. They can live autonomously, providing full cycles of substances and preventing live activity products poisoning.

The Anoxybacillus flavithermus KU2-6-11 was isolated from sediments of a nameless hot spring. The hot spring is located in Uzon caldera (Kamchatka, Russia). The sequenced and annotated genome is 2,646,305 bp and encodes 2787genes. The draft genome sequence of the Anoxybacillus flavithermus KU2-6-11 has been deposited at DDBJ/EMBL/GenBank under the accession PEDM01000000 and the sequences could be found at the site https://www.ncbi.nlm.nih.gov/nuccore/PEDM01000000.

A new strain, Geobacillus stearothermophilus 22, was isolated from the Garga hot spring in the Bargusin Valley, Baikal Region, Russia. The morphology and biochemistry of the strain were analyzed, and full genome sequencing was conducted. The sequence was subjected to bioinformatics analysis. The nucleotide sequences (contigs) of the strain were found to be similar to the genome of the thermophilic strain G. kaustophilus Y412MC52. The proteome of the new strain was analyzed. Enzymes that belong to hemicellulases (endoxylanase, beta-xylosidase, and arabinofuranosidase) and the endocellulase enzyme were detected.

Adaptive capacity of bacteria and archaea from salt lakes of the Altai Region are discussed. It is established that halophilic archaea (genus Halorubrum) and halotolerant bacteria (genus Halomonas) grow in a wide range of pH and mineralization (in the presence of Cl−, SO42−, ClO4−, Mg2+) and survive at low temperatures with a minor decrease in viability.

Approaches are considered for the search for novel sources of non-food, renewable raw materials for third-generation biofuel production, namely, microalgae strains inhabiting natural systems of Western Siberia. This regional biodiversity survey is of great interest in connection with the vast habitat areal and the limited research on the properties of microalgae. During the work, a number of strains was isolated; one of them, Chlorella spp. A1125, has the necessary characteristics for cultivation in a pilot photobioreactor, including a maximum lipid productivity of 0.081 g/L (23% of the dry cell weight) with growth in minimal media. The strain is characterized by the content of both saturated fatty acids C16:0 (25%) and unsaturated fatty acids C16:2 (16%) and C18:2 (27%), making it a promising candidate for the third-generation biofuel production.

We analyze the distribution of chemical elements in microbial communities from various hydrothermal ecosystems (the Kurile-Kamchatka volcanic belt, the Baikal rift zone) and various laboratory cultures by means of microXFA-SR. We describe various techniques for combining optical and microXFA-SR X-ray cell images. The combination of images allows us to demonstrate the accumulation of chemical elements in cells of bacteria, cyanobacteria, and diatom and green algae.

Numerous bitter lakes, largely closed and shallow, are concentrated in a small area of the South of Western Siberia (Kulunda and Barabinsk steppes). Most lakes are marked by the development of thick black or grayish blue silt organogenic sediments formed due to the dying-off of local halophilic organisms. Salt lakes are of great interest for scientists. The investigation was conducted in the context of complex biological and biochemical studies aimed at identifying regularities in the redistribution of elements between components of a salt-lake system by SR-XRF (Synchrotron Radiation X-ray Fluorescence).

The contents of many elements in a microbial community and various associations of a carbonate body from the Garga hot spring (Barguzin Valley, Baikal Rift Zone) were analyzed with a synchrotron X-ray fluorescence analysis. The coefficients of biological accumulation have been determined. The contents of practically all elements, except for Sr, in the microbial community are higher than in the carbonate body, and the Ge and Zn contents are higher by an 2 order of magnitude. The vertical cross section of the carbonate body contains three associations two of which formed as a result of microbial activity. The contents of elements in all associations are similar. The Ge content in the microbial community is 270 ppm, on average, whereas in the carbonate body it is less than 2 ppm. The elevated Ge contents could serve as a diagnostic indicator of the microbial community’s development around the sulfide-less alkaline hot springs in the presence of increased contents of radium isotopes. A sample of the carbonate body with layers formed as a result of the microbial community activity was continuously scanned with a step of 0.5 mm. No Ge-rich areas were determined, which indicates its removal by solutions during the destruction of organic matter.

The role of fine sediments of technogenic origin in channel process is analyzed. The specific features of sedimentation of particles with different density and shape and the issues of flocculation and consolidation of sediments in the bottom part of flow are discussed. Experimental data on the adhesion of particles are given and a relationship for its assessment is proposed. The class of sediments for which the adhesion determines the critical erosion velocity is determined. The processes of river water self-purification and precipitation of fine sediments were compared to show that sedimentation processes play an important role in river water self-purification.

The features of present deposits that form in the vicinity of hot springs can provide clues to the parameters of paleowaters in places of past hydrothermal activity marked by remnant carbonate and/or siliceous sinter. We investigated a large carbonate body at the Garga hot spring developing in the Baikal zone of nitric hydrotherms in the Barguzin Rift Zone valley. The main focus was on the structure of the carbonate mound, as well as on the partitioning of radioactive elements between the cyanobacterial mat and the inorganic component of the body (the issue that has never been explored before). The cyanobacterial community of the Garga spring is an active biosorbent of 226Ra, 228Ra, 210Pb. The radionuclides accumulated by biosorption become preserved in minerals that form within the bacterial community. The reported data of mineral formation in the cyanobacterial mat along with the mineralogy and structure of the carbonate mound of the Garga spring have implications for the complex history of the Garga body. It has been produced jointly by precipitation from the venting thermal water (opal-calcite-fluorite-barite-celestine assemblage) and microbial metabolic activity (coarse calcite and thin black encrustation rich in Mn minerals).