The microbial ecology of permafrost

Key Points Permafrost is a unique habitat for cold-adapted microbial life on Earth and is a model environment for extraterrestrial biomes. Permafrost microorganisms have several strategies for survival under cold conditions. Different permafrost habitats in the Arctic and Antarctica harbour a diversity of microorganisms, many of which exhibit activity at subzero temperatures. Permafrost thaw results in different types of landscape features that can influence microbial composition and activity. Much of the current knowledge of permafrost microbiology was obtained from the study of permafrost isolates, but recent advances in high-throughput sequencing technologies have enabled the detailed exploration of permafrost microbial communities without the necessity for cultivation. The microbial ecology of permafrost is the focus of intensifying interest, owing to the uncertainty of the effects of climate change on the microbial cycling of carbon that is currently sequestered in permafrost. One-quarter of the land surface on Earth is underlain by permafrost. Jansson and Taş review the microbial ecology of this fascinating and unique niche, pulling together observations from the study of permafrost isolates and the application of high-throughput sequencing. Permafrost constitutes a major portion of the terrestrial cryosphere of the Earth and is a unique ecological niche for cold-adapted microorganisms. There is a relatively high microbial diversity in permafrost, although there is some variation in community composition across different permafrost features and between sites. Some microorganisms are even active at subzero temperatures in permafrost. An emerging concern is the impact of climate change and the possibility of subsequent permafrost thaw promoting microbial activity in permafrost, resulting in increased potential for greenhouse-gas emissions. This Review describes new data on the microbial ecology of permafrost and provides a platform for understanding microbial life strategies in frozen soil as well as the impact of climate change on permafrost microorganisms and their functional roles.