Isolation of facultatively anaerobic soil bacteria from Ny-A° lesund, Svalbard

Abstract

Anaerobic conditions in soil commonly occur even in upland environments. Physiological and biogeochemical properties of individual anaerobic bacteria, however, have been poorly understood due to difficulties in culture. This study aimed to isolate anaerobic bacteria in the Arctic tundra soil and to identify their physiological characteristics. Anaerobic culture and 16S rRNA gene sequence-based phylogenetic analysis showed that total 33 bacterial strains were affiliated with 15 species from the following 8 genera: Bacillus, Carnobacterium, Clostridium, Paenibacillus, and Trichococcus (Firmicutes), Pseudomonas and Rahnella (Gamma-proteobacteria) and Cellulomonas (Actinobacteria). All isolates were identified as facultatively anaerobic bacteria this finding might be partially attributed to the characteristics of sampling sites, which temporarily developed anaerobic conditions because of the presence of stagnant melting snow. Six of the 33 bacterial strains were revived subsequently from glycerol stocks held -80 °C, and these were used for the physiological study: four isolates from Firmicutes, one isolate from Gamma-proteobacteria and one isolate from Actinobacteria. Five isolates except KOPRI 80146 (Bacillus sp.) could grow at either 4 °C or 10 °C within a week. All six isolates showed cellulase or protease activities at 10 °C or 15 °C. Endospores were observed from four isolates belonging to Firmicutes. These physiological characteristics may contribute to the survival of these organisms at low temperatures and to their involvement in biogeochemical cycles in the tundra soil. These isolates may be used for further detailed studies for identifying their cold-adaptation mechanisms and ecological roles in the Arctic.