Original Article

Subject Category: Microbial ecology and functional diversity of natural habitats

The ISME Journal (2007) 1, 256–264; doi:10.1038/ismej.2007.34; published online 7 June 2007

Cultivation of a novel cold-adapted nitrite oxidizing betaproteobacterium from the Siberian Arctic

Mashal Alawi1, André Lipski2, Tina Sanders1,  Eva-Maria-Pfeiffer3 and Eva Spieck1

  1. 1Department of Biology, Biocenter Klein Flottbek, University of Hamburg, Hamburg, Germany
  2. 2Department of Microbiology, Fachbereich Biologie/Chemie, University of Osnabrück, Osnabrück, Germany
  3. 3Department of Geowissenschaften, Institute of Soil Science, University of Hamburg, Hamburg, Germany

Correspondence: Dr E Spieck, Department of Biology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststr. 18, 22609 Hamburg, Germany. E-mail: spieck@mikrobiologie.uni-hamburg.de

Received 26 February 2007; Revised 21 April 2007; Accepted 21 April 2007; Published online 7 June 2007.

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Abstract

Permafrost-affected soils of the Siberian Arctic were investigated with regard to identification of nitrite oxidizing bacteria active at low temperature. Analysis of the fatty acid profiles of enrichment cultures grown at 4°C, 10°C and 17°C revealed a pattern that was different from that of known nitrite oxidizers but was similar to fatty acid profiles of Betaproteobacteria. Electron microscopy of two enrichment cultures grown at 10°C showed prevalent cells with a conspicuous ultrastructure. Sequence analysis of the 16S rRNA genes allocated the organisms to a so far uncultivated cluster of the Betaproteobacteria, with Gallionella ferruginea as next related taxonomically described organism. The results demonstrate that a novel genus of chemolithoautotrophic nitrite oxidizing bacteria is present in polygonal tundra soils and can be enriched at low temperatures up to 17°C. Cloned sequences with high sequence similarities were previously reported from mesophilic habitats like activated sludge and therefore an involvement of this taxon in nitrite oxidation in nonarctic habitats is suggested. The presented culture will provide an opportunity to correlate nitrification with nonidentified environmental clones in moderate habitats and give insights into mechanisms of cold adaptation. We propose provisional classification of the novel nitrite oxidizing bacterium as 'Candidatus Nitrotoga arctica'.

Keywords:

cold adaptation, nitrification, nitrite oxidation, permafrost

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