High Diversity of Diazotrophs in the Forefield of a Receding Alpine Glacier
High Diversity of Diazotrophs in the Forefield of a Receding Alpine Glacier
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DOI：
10.1007/s00248-008-9408-5
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发表时间：
2009-01-01
影响因子：
3.6
通讯作者：
Zeyer, Josef
中科院分区：
文献类型：
--
作者：
Duc, Laurence;Noll, Matthias;Zeyer, Josef
消退的冰川的前场是代表自然时间序列的独特而敏感的环境。在这样的生境中，微生物固氮特别重要，因为生物有效氮的低浓度是植物和土壤微生物生长的关键限制之一。用乙炔还原试验评价了达玛冰川(瑞士中央阿尔卑斯山)土壤中的非共生固氮作用。通过组装两个土龄级(8年和70年无冰FOREFIELD)的土壤和根际土壤的4个nifH序列文库，研究了自由生活的重氮营养多样性和种群结构。共分析了318个nifH序列，并将其归类为45个独特的系统型。系统发育分析显示，与以前在其他环境中观察到的相比，nifH序列在系统发育簇中具有更高的多样性和更广泛的分布。这说明了在这种营养贫乏的环境中，自由生活的重氮菌及其对全球氮输入的潜在贡献的重要性。土壤中NifH多样性高于根际土壤。此外，四个文库的相似度较低。这表明土壤年龄和先锋植物的存在都影响着自由生活的固氮菌的多样性和种群结构。
Forefields of receding glaciers are unique and sensitive environments representing natural chronosequences. In such habitats, microbial nitrogen fixation is of particular interest since the low concentration of bioavailable nitrogen is one of the key limitations for growth of plants and soil microorganisms. Asymbiotic nitrogen fixation in the Damma glacier (Swiss Central Alps) forefield soils was assessed using the acetylene reduction assay. Free-living diazotrophic diversity and population structure were resolved by assembling four NifH sequence libraries for bulk and rhizosphere soils at two soil age classes (8- and 70-year ice-free forefield). A total of 318 NifH sequences were analyzed and grouped into 45 unique phylotypes. Phylogenetic analyses revealed a higher diversity as well as a broader distribution of NifH sequences among phylogenetic clusters than formerly observed in other environments. This illustrates the importance of free-living diazotrophs and their potential contribution to the global nitrogen input in this nutrient-poor environment. NifH diversity in bulk soils was higher than in rhizosphere soils. Moreover, the four libraries displayed low similarity values. This indicated that both soil age and the presence of pioneer plants influence diversification and population structure of free-living diazotrophs.