Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan.
FEMS Microbiol Ecol. 2013 Apr;84(1):98-109. doi: 10.1111/1574-6941.12042. Epub 2012 Dec 17.
In spite of the ecological importance of protists, very little data is available on their distribution in soil. This investigation is the first of its kind on what could be the major components of the soil protistan community, the Myxomycetes, or plasmodial slime-moulds, a monophyletic class in the phylum Amoebozoa. Myxomycetes have a complex life cycle culminating in the formation of mainly macroscopic fruiting bodies, highly variable in shape and colour, which can be found in every terrestrial biome. Despite their prevalence, they are paradoxically absent from environmental DNA sampling studies. We obtained myxomycete SSU rRNA gene sequences from soil-extracted RNAs using specific primers. Soil samples were collected in three mountain ranges (France, Scotland and Japan). Our study revealed an unexpectedly high diversity of dark-spored Myxomycetes, with the recovery of 74 phylotypes. Of these, 74% had < 98% identity with known sequences, showing a hidden diversity; there was little overlap between localities, implying biogeographical patterns. Few phylotypes were dominant and many were unique, consistent with the 'rare biosphere' phenomenon. Our study provides the first detailed insight into the community composition of this ecologically important group of protists, establishing means for future studies of their distribution, abundance and ecology.
尽管原生动物在生态上很重要，但关于它们在土壤中的分布的数据却很少。本研究首次针对土壤原生动物群落的主要组成部分——黏菌（或质型黏菌，变形体动物门的一个单系类群）进行了调查。黏菌具有复杂的生命周期，最终形成主要的宏观生殖体，其形状和颜色高度可变，在每个陆地生物群系中都可以找到。尽管它们很普遍，但在环境 DNA 采样研究中却出人意料地缺失。我们使用特定引物从土壤提取的 RNA 中获得了黏菌 SSU rRNA 基因序列。土壤样本采集自三个山脉（法国、苏格兰和日本）。我们的研究揭示了一种出乎意料的高多样性的深色孢子黏菌，共回收了 74 个系统发育型。其中，74%的系统发育型与已知序列的相似度<98%，表明存在隐藏的多样性；不同地点之间的重叠很少，暗示存在生物地理模式。很少有系统发育型占主导地位，许多是独特的，这与“稀有生物圈”现象一致。我们的研究首次详细了解了这个生态重要的原生动物群体的群落组成，为未来研究它们的分布、丰度和生态提供了手段。
