Volume 16, Issue 10 p. 3250-3262
Research article

The nitrogen cycle in cryoconites: naturally occurring nitrification-denitrification granules on a glacier

Takahiro Segawa

Corresponding Author

Takahiro Segawa

National Institute of Polar Research, Tokyo, Japan

Transdisciplinary Research Integration Center, Tokyo, Japan

These authors contributed equally to this study.For correspondence. E-mail [email protected]; Tel. +81 42 512 0768; Fax +81 42 528 3492.Search for more papers by this author
Satoshi Ishii

Satoshi Ishii

Division of Environmental Engineering, Hokkaido University, Sapporo, Japan

These authors contributed equally to this study.Search for more papers by this author
Nobuhito Ohte

Nobuhito Ohte

Laboratory of Forest Hydrology and Erosion Control Engineering, Department of Forest Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan

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Ayumi Akiyoshi

Ayumi Akiyoshi

National Institute of Polar Research, Tokyo, Japan

Transdisciplinary Research Integration Center, Tokyo, Japan

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Akinori Yamada

Akinori Yamada

Department of Biological Sciences, Tokyo Institute of Technology, Tokyo, Japan

Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Nagasaki, Japan

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Fumito Maruyama

Fumito Maruyama

Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, Japan

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Zhongqin Li

Zhongqin Li

Laboratory of Cryosphere and Environment/Tien Shan Glaciological Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, China

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Yuichi Hongoh

Yuichi Hongoh

Department of Biological Sciences, Tokyo Institute of Technology, Tokyo, Japan

These authors contributed equally to this study.Search for more papers by this author
Nozomu Takeuchi

Nozomu Takeuchi

Department of Earth Sciences, Graduate School of Science, Chiba University, Chiba, Japan

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First published: 20 June 2014
Citations: 59

Summary

Cryoconites are microbial aggregates commonly found on glacier surfaces where they tend to take spherical, granular forms. While it has been postulated that the microbes in cryoconite granules play an important role in glacier ecosystems, information on their community structure is still limited, and their functions remain unclear. Here, we present evidence for the occurrence of nitrogen cycling in cryoconite granules on a glacier in Central Asia. We detected marker genes for nitrogen fixation, nitrification and denitrification in cryoconite granules by digital polymerase chain reaction (PCR), while digital reverse transcription PCR analysis revealed that only marker genes for nitrification and denitrification were abundantly transcribed. Analysis of isotope ratios also indicated the occurrence of nitrification; nitrate in the meltwater on the glacier surface was of biological origin, while nitrate in the snow was of atmospheric origin. The predominant nitrifiers on this glacier belonged to the order Nitrosomonadales, as suggested by amoA sequences and 16S ribosomal RNA pyrosequencing analysis. Our results suggest that the intense carbon and nitrogen cycles by nitrifiers, denitrifiers and cyanobacteria support abundant and active microbes on the Asian glacier.