Salinity-induced succession of phototrophic communities in a southwestern Siberian soda lake during the solar activity cycle.

A variety of lakes located in the dry steppe area of southwestern Siberia are exposed to rapid climatic changes, including intra-century cycles with alternating dry and wet phases driven by solar activity. As a result, the salt lakes of that region experience significant fluctuations in water level and salinity, which have an essential impact on the indigenous microbial communities. But there are few microbiological studies that have analyzed this impact, despite its importance for understanding the functioning of regional water ecosystems.

A novel bacteriobiont of the Arctic lichen Flavocetraria nivalis, Lichenifustis flavocetrariae gen. nov, sp. nov. demonstrating hydrolytic properties and containing a full set of the Calvin-Benson-Bassham cycle genes.

A Gram-negative, strictly aerobic, chemoorganotrophic, bacteriochlorophyll a-containing, slow-growing bacterium was isolated from the lichen Flavocetraria nivalis and designated strain BP6-180914. Cells of this strain were large nonmotile rods, which reproduced by binary fission. Cells grew under oxic conditions and were able to utilize sugars and several polysaccharides, including starch and pectin.

Biogeochemical Activity of Methane-Related Microbial Communities in Bottom Sediments of Cold Seeps of the Laptev Sea.

Bottom sediments at methane discharge sites of the Laptev Sea shelf were investigated. The rates of microbial methanogenesis and methane oxidation were measured, and the communities responsible for these processes were analyzed. Methane content in the sediments varied from 0.

Biogeochemical Factors of Cs, Sr, U, Pu Immobilization in Bottom Sediments of the Upa River, Located in the Zone of Chernobyl Accident.

Laboratory modeling of Cs, Sr, U, Pu immobilization by phytoplankton of the river Upa, affected after the Chernobyl accident, has been carried out. Certain conditions are selected for strong fixation of radionuclides in bottom sediments due to biogeochemical processes. The process of radionuclide removal from the water phase via precipitation was based on their accumulation by phytoplankton, stimulated by nitrogen and phosphorus sources.

History of the Study of the Genus : From the First Enrichment Cultures to Pangenomic Analysis.

Representatives of the genus are filamentous, sulfur-oxidizing bacteria found in flowing waters with counter-oriented sulfide and oxygen gradients. They were first described at the end of the 19th century, but the first pure cultures of this species only became available 100 years later. An increase in the number of described species at the beginning of the 21st century shows that the classical phylogenetic marker, 16S rRNA gene, is not informative for species differentiation, which is possible based on genome analysis.

Ecology and biogeography of the 'marine Geitlerinema' cluster and a description of Sodalinema orleanskyi sp. nov., Sodalinema gerasimenkoae sp. nov., Sodalinema stali sp. nov. and Baaleninema simplex gen. et sp. nov. (Oscillatoriales, Cyanobacteria).

Filamentous cyanobacteria belonging to the 'marine Geitlerinema' cluster are spread worldwide in saline environments and considered to play an important ecological role. However, the taxonomy of this group remains unclear. Here, we analyzed the phylogeny, ecology and biogeography of the 'marine Geitlerinema' cluster representatives and revealed two subclusters: (1) an 'oceanic' subcluster containing PCC7105 clade and black band disease (BBD) clade with free-living and pathogenic strains distributed in Atlantic, Indian and Pacific Ocean-related localities, and (2) a Sodalinema subcluster containing free-living strains from marine, hypersaline, saline-alkaline and soda lake habitats from the Eurasian and African continents.

Methanogenesis in the Lake Elton saline aquatic system.

Cultivation and molecular approaches were used to study methanogenesis in saline aquatic system of the Lake Elton (southern Russia), the largest hypersaline lake in Europe. The potential rates of hydrogenotrophic, acetoclastic, methylotrophic and methyl-reducing methanogenesis and diversity of the growth-enriched for by adding electron donors methanogenic communities were studied in the sediment slurry incubations at salinity range from 7 to 275 g/L. The most active pathway detected at all salinities was methylotrophic with a dominance of Methanohalobium and Methanohalophilus genera, at salt saturation and moderately halophilic Methanolobus and Methanococcoides at lower salinity.

The patterns of nitrogen fixation in haloalkaliphilic phototrophic communities of Kulunda Steppe soda lakes (Altai, Russia).

Nitrogen fixation (NF) of phototrophic communities was studied in a number of soda lakes with a wide range of salinity (25-400 g/l) located in Kulunda Steppe (Altai, Russia) during several summer seasons (2011-2016). The phototrophic communities were represented by the algal-bacterial Ctenocladus communities or cyanobacterial biofilms dominated by heterocystous and non-heterocystous cyanobacteria and purple sulfur bacteria Ectothiorhodospira sp. (up to 210 g/l) and endoevaporitic Euhalothece communities dominated by the extremely salt-tolerant unicellular cyanobacterium Euhalothece sp.

Effect of salinity on diazotrophic activity and microbial composition of phototrophic communities from Bitter-1 soda lake (Kulunda Steppe, Russia).

Bitter-1 is a shallow hypersaline soda lake in Kulunda Steppe (Altai region, Russia). During a study period between 2005 and 2016, the salinity in the littoral area of the lake fluctuated within the range from 85 to 400 g/L (in July of each year). Light-dependent nitrogen fixation occurred in this lake up to the salt-saturating conditions.