ISSN 0147-6874, Moscow University Soil Science Bulletin, 2011, Vol. 66, No. 2, pp. 45–49. © Allerton Press, Inc., 2011. Original Russian Text © M.S. Dubrova, D.A. Lubsanova, E.P. Makarova, P.A. Kozhevin, N.A. Manucharova, G.M. Zenova, 2011, published in Vestnik Moskovskogo Universiteta. Pochvovedenie, 2011, No. 2, pp. 3–8. 45 INTRODUCTION It has long been thought that actinomycetes adapt to low temperatures with difficulty and rarely inhabit cold sites. Recent data have shown the isolation of psychrotolerant actinomycetes from land and water ecosystems, arctic sand rocks, forest mountain and meadow soils, Norwegian fiords, polar ice, and soils of the Arctic regions [4, 7, 10]. As follows from the investigations performed, soil psychrotolerant actinomycetes grow and develop actively in northern soils, including peat soils, charac- terized by unfavorable conditions for most organisms: high water saturation, anaerobiosis, low pH values, deficit of foodstuff, presence of toxic compounds, and low temperatures not exceeding 10°C even on the surface in summer. They form mycelium and make an integral part of the hydrolytic microbial population participating in the decomposition of plant residues [1]. Investigations of actinomycetes inhabiting soils and plant substrata of cold sites not only expand the conception of the ecological niches of mycelial bacte- ria, but also establish producers of new biologically active substances among cold-resistant species. This work was performed to investigate the role of psychrotolerant actinomycetes in soil actinomycete complexes, their temperature growth range, and their functional specificity in cold soils of the tundra and taiga. OBJECTS AND METHODS OF INVESTIGATION Typical tundra peat cryogenic soil (Yamal Penin- sula) and coarse-humic gley soil (near Vorkuta), as well as northern taiga gley low-podzolic soil (Nadym District), were investigated. These soils are cold, fro- zen, and characterized by negative average annual temperatures at a depth of 10 cm. Northern taiga soils such as gypsic podzolic soil, gray humic cultivated soil petrozem (Chuga Reserve, Archangelsk Region), humic gley pelozem (Pinega Reserve, Archangelsk Region), and iron-bearing podzolic soil (Solovetsky Islands, Archangelsk Region) are characterized by positive average annual temperatures (4–8°C) (table). Traditional plating soil and plant suspension dilu- tions onto Gauze agar medium 1 were applied to iso- late and register actinomycetes in the soils under investigation. Taking into account the temperature range and growth optima of the studied mesophylic and psychrotolerant actinomycetes, the plates were incubated at 5, 20, and 28°C. The phylogenetic position of isolated psychrotoler- ant actinomycetes (strain 5-4-1 and moss 18) was esti- mated on the basis of 16S rRNA gene sequencing. DNA was extracted from the bacterial biomass using a Wizard Genomic DNA Purification Kit (Promega, United States) according to the recommendations of the producer with certain modifications [2]. A univer- sal primer system was used to perform polymerase chain reaction and further sequencing of PCR frag- ments of the 16S rRNA gene [6, 8]. A full-size copy of the gene was obtained with a Mastercycler Personal device (Eppendorf 11F, Germany) using the following Psychrotolerant Actinomycetes in Soils of the Tundra and Northern Taiga M. S. Dubrova, D. A. Lubsanova, E. P. Makarova, P. A. Kozhevin, N. A. Manucharova, and G. M. Zenova Faculty of Soil Science, Moscow State University, Moscow, 119899 Russia E-mail: kozhevinpa@mail.ru, zenova38@mail.ru Received December 21, 2010 Abstract—Actinomycetes adapted to low-temperature conditions are present in the cold soils of the tundra and northern taiga in quantities comparable to mesophylic forms and dominate in the soil actinomycete com- plex. Actinomycetes isolated from cold soils were identified as Streptomyces. Most actinomycetes relate to psychrotolerant forms according to habitation temperature. Two of them are conditionally psychrophilic. Specific properties of the investigated populations were identified by multirespirometrical testing. Keywords: psychrotolerant actinomycetes and soil. DOI: 10.3103/S0147687411020037