Cowan Don A, Makhalanyane Thulani P, Dennis Paul G, Hopkins David W
Department of Genetics, Centre for Microbial Ecology and Genetics, University of Pretoria Pretoria, South Africa.
School of Agriculture and Food Sciences, The University of Queensland Brisbane, QLD, Australia.
Front Microbiol. 2014 Apr 9;5:154. doi: 10.3389/fmicb.2014.00154. eCollection 2014.
The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbor microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths) possess a genetic capacity for nitrogen and carbon cycling, polymer degradation, and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities.
南极洲干谷被视为地球上最寒冷的超干旱沙漠系统。虽然包括极低的最低温度、频繁的冻融循环和低水可用性在内的各种环境压力因素对生命构成了严重限制，但仍存在适合大量微生物定殖的生态位。南极沙漠土壤中的微生物多样性水平比以前认为的要高得多。土壤生态位，包括隐蔽和避难栖息地、微生物垫和永久冻土，都栖息着驱动关键生物地球化学循环过程的微生物群落。例如，石内生物（石下生物和石内生物）具有氮和碳循环、聚合物降解及其他系统过程的遗传能力。通过乙炔还原试验评估的石下生物的固氮率表明，这些群落是这些贫营养土壤中氮的重要输入源。在此，我们综述南极土壤中微生物多样性的各个方面，重点关注其功能和能力。我们评估了目前关于适应南极土壤环境的知识，并强调了南极沙漠土壤群落目前面临的威胁。
