The soil food web revisited: Diverse and widespread mycophagous soil protists
The soil food web revisited: Diverse and widespread mycophagous soil protists
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DOI：
10.1016/j.soilbio.2015.11.010
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发表时间：
2016-03-01
影响因子：
9.7
通讯作者：
Bonkowski, Michael
中科院分区：
文献类型：
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作者：
Geisen, Stefan;Koller, Robert;Bonkowski, Michael
土壤原生生物通常被认为是唯一的食菌动物，与食菌线虫一起作为土壤食物网中细菌能量通道的主要控制器。相反，真菌的能量通道被认为是由节肢动物和真菌食性线虫控制的。然而，被大多数土壤生物学家接受的这一观点受到了分类学家进行的功能研究的挑战，这些研究揭示了一系列以真菌为食的原生生物。为了增加对食真菌原生生物功能重要性的认识，我们分离并启动了原生生物类群的培养，并在微型实验中测试了8种兼性摄食不同真菌的原生类群。两种不同鞭毛的Cercomonas属，被种隐形阿米巴CryptoDifflugia perculata和四属裸阿米巴(棘阿米巴，细粘虫Leptomyxa sp.，两个Mayorella spp.和阿米巴属(Tecameba spp.)用4个分类群(Cercomonas sp.、Leptomyxa sp.、Mayorella sp.和Thecamoeba sp.)为了确定真菌吞噬原生生物在环境中的潜在重要性，我们应用了一种数据挖掘方法，针对从五个根本不同的陆地样本的后转录中获得的小亚基(SSU)rRNA数据。我们重点分析了两个研究较好的食菌性原生动物类群的分布和相对丰度，它们是吸血鬼类阿米巴虫和巨型纤毛虫。这两组在所有高度反差的陆地样本中都被检测到，占所有原生生物SSU rRNA转录本的3%。这两组原生生物的SSU转录本与所有剩余的原生生物SSU转录本相比，与真菌序列的相对丰度显示出很强的相关性，表明土壤原生生物之间存在着密切的直接营养相互作用。综上所述，这项研究提供了证据，表明土壤原生生物之间的真菌吞噬现象在陆地生态系统中是常见的，可能是实质性的，但迄今被忽视了生态重要性。未来的研究应该着眼于评估特定分类群(兼性)的真菌吞噬作用，破译真菌群落中引起的变化，并定量评估这种营养位置在土壤生态系统中的功能重要性。(C)2015爱思唯尔有限公司。保留所有权利。
Soil protists are commonly suggested being solely bacterivorous, serving together with bacterivorous nematodes as the main controllers of the bacterial energy channel in soil food webs. In contrast, the fungal energy channel is assumed to be controlled by arthropods and mycophagous nematodes. This perspective accepted by most soil biologists is, however, challenged by functional studies conducted by taxonomists that revealed a range of mycophagous protists. In order to increase the knowledge on the functional importance of mycophagous protists we isolated and initiated cultures of protist taxa and tested eight for facultative feeding on diverse fungi in microcosm experiments. Two different flagellate species of the genus Cercomonas, the testate amoeba Cryptodifflugia operculata and four genera of naked amoebae (Acanthamoeba sp., Leptomyxa sp., two Mayorella spp. and Thecamoeba spp.) fed and grew on yeasts with four taxa (Cercomonas sp., Leptomyxa sp., Mayorella sp., and Thecamoeba sp.) also thriving on spores of the plant pathogenic hyphal-forming fungus Fusarium culmorum.To identify the potential importance of mycophagous protists in the environment we applied a data mining approach targeting small subunit (SSU) rRNA data obtained in metatranscriptomes of five fundamentally different terrestrial samples. We focused our analyses on the distribution and relative abundances of two well-studied mycophagous protist groups, vampyrellid amoebae and grossglockneriid ciliates. Both groups were detected in all of the highly contrasting terrestrial samples, comprising up to 3% of all protist SSU rRNA transcripts. SSU transcripts of these two groups, in contrast to all remaining protist SSU transcripts, showed strong correlations with the relative abundance of fungal sequences indicating close direct trophic interactions.Taken together, this study provides evidence that mycophagy among soil protists is common and might be of substantial but hitherto overlooked ecological importance in terrestrial ecosystems. Future studies should aim at evaluating taxon-specific (facultative) mycophagy, decipher changes caused in the fungal community and quantitatively evaluate the functional importance of this trophic position in soil ecosystems. (C) 2015 Elsevier Ltd. All rights reserved.