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Data indicating the important role of microorganisms in the formation of nodular monazite (NM) (kularite) of the Kular Range, Republic of Sakha (Yakutia), are presented. The NM contains microorganisms (cyanobacteria) replaced by REE-bearing phosphate (monazite) in the form of stromatolitic microedifices, as well as framboidal Fe sulfides in monazite. The Corg isotopic composition of kularite corresponds to biogenic carbon: the δ13С values vary from –22.2 to –22.3‰. [ABSTRACT FROM AUTHOR]

Soda lakes are relic ecosystems inhabited by unique microorganisms, which are doubly extremophilic: both haloalkaliphilic and natronophilic. Two morphologically and physiologically similar monocultures of filamentous anoxygenic phototrophic bacteria (FAPB) were isolated from the water samples and biofilms on plants of the coastal zones of the steppe soda lakes Tanatar 6 and Gorchina 1 (Kulunda, Altai krai) during the season of their desalination. In their natural environments, FAPB coexisted with anoxygenic purple sulfur bacteria of the genera Chromatium,Thiocapsa, Ectothiorhodospira, and Thiorhodospira, as well as with oxygenic phototrophs (alkaliphilic cyanobacteria, euglenophytes, and diatoms). FAPB formed filaments surrounded by thin sheaths; their cells contained antenna structures (chlorosomes). Apart from small amounts of bacteriochlorophyll (BChl) a in the reaction center, both isolates contained also antenna BChl c and BChl d. Alpha- and beta-carotenes and their derivatives were also detected. FAPB grew well in the medium containing Na2S ∙ 9H2O (500 mg/L) at total mineralization of 15−30 g/L and pH 8−9.5. Identification of both cultures based on amino acid composition of the PufLM complex revealed that they belonged to the phylum Chloroflexi and were almost 100% identical both to each other and to the halo-alkaliphilic isolate "Candidatus Viridilinea mediisalina" Kir15-3F revealed previously in the Kiran soda lake (Eastern Siberia, Russia). It may be concluded that "Cand. Viridilinea mediisalina" is a typical component of Siberian soda lakes with moderate salinity. [ABSTRACT FROM AUTHOR]