MICROBIAL REDUCTION OF Fe(III) IN SAMPLES OF TUNDRA SOILS from the EAST SIBERIAN ARCTIC
A.G. Zakharyuk1, V.E. Trubitsyn1, T.A. Vishnivetskaya2, E.M. Rivkina2, V.A. Shcherbakova1
1Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Russia
2Institute of Physicochemical and Biological Problems of Soil Science, Russian Academy of Sciences, Pushchino, Russia
Keywords: tundra zone soils, Arctic, iron reduction, anaerobic communities, metagenome
Abstract
Enrichment cultures of psychrophilic and psychrotolerant bacteria capable of reducing ferric iron at temperatures of 6 to 15 °C were obtained from samples of two tundra soils from the Bykovsky Peninsula (Northern Yakutia, eastern sector of Russian Arctic). The highest concentrations of Fe(II) ions were observed in enrichment cultures grown with the use of a soluble ferric salt in the form of Fe(III) citrate. Furthermore, anaerobic communities from two enrichment cultures derived from permafrost soil samples of the Mammoth Khayata tract and cultivated at 15 °C demonstrated a preference for insoluble Fe(III) oxide as an electron acceptor while utilizing acetate and formate as electron donors. Experimental data on the composition of microbial communities inhabiting permafrost soils were obtained through molecular biology and bioinformatics methods. Notably, this study presents a novel comparison between the composition of a naturally occurring microbial community that developed over an extended period under natural conditions at low temperatures, and a laboratory-cultivated microbial community. The results demonstrate that prokaryotic communities of the soils of Arctic ecosystems of Yakutia are phylogenetically diverse despite the cold and oligotrophic (nutrient-poor) conditions. While representatives of Proteobacteria and Actinobacteria phyla dominate in natural samples of tundra soil (~30-50 %), the cultivated microbial community obtained in vitro from natural samples was dominated by Firmicutes (38 %).
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