Unveiling Trophic Functions of Uncultured Protist Taxa by Incubation Experiments in the Brackish Baltic Sea
Unveiling Trophic Functions of Uncultured Protist Taxa by Incubation Experiments in the Brackish Baltic Sea
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DOI：
10.1371/journal.pone.0041970
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发表时间：
2012-07-30
期刊：
影响因子：
3.7
通讯作者：
Juergens, Klaus
中科院分区：
文献类型：
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作者：
Weber, Felix;del Campo, Javier;Juergens, Klaus
背景资料：由于分子调查和下一代测序方法，我们对水生原生生物的生殖和多样性的了解正在迅速增加。这导致了从文化中已知的类群和从环境18 S rRNA基因序列中已知的类群之间的相当大的差异。因此，它通常是很难分配生态功能的新类群检测文化独立的molecular approaches.Methodology/主要发现：一个未修正的黑暗孵育和18 S rRNA测序的组合被选择链接的分子多样性数据的未培养的原生生物异养，大概是噬菌的，增长。孵化，进行波罗的海半咸水，导致在一个一致的转变，从原生生物群落占主导地位的光养生物，其中异养生物占主导地位。这是根据指纹分析和克隆文库中的细胞丰度和18 S rRNA序列确定的。大部分的丰富的类孵化后，到目前为止未培养的海洋类群内的金藻，ochrophytes，choanoflagellates，尾虫，picobiliphytes，主要是在最近建立的或在这里定义的环境分支。它们在黑暗中的生长，以及具有类似目的的研究的一致结果，提供了这些未培养的类群代表异养或兼养物种的证据。结论/意义：这些发现揭示了各种未培养原生生物的营养作用，特别是在功能异质的群体中（例如，金生植物、赭色植物）和似乎在营养方面令人困惑的类群（微微型植物）。此外，我们的研究结果表明，在波罗的海西南部的异养鞭毛虫群落占主导地位的海洋起源的物种。未经修改的孵育与分子多样性分析相结合，因此被确认为一个有前途的方法，探索营养模式的环境相关的原生生物类群，目前只有序列数据。
Background: Our knowledge of the phylogeny and diversity of aquatic protists is rapidly increasing due to molecular surveys and next-generation sequencing approaches. This has led to a considerable discrepancy between the taxa known from cultures and those known from environmental 18S rRNA gene sequences. Hence, it is generally difficult to assign ecological functions to new taxa detected by culture-independent molecular approaches.Methodology/Principal Findings: A combination of unamended dark incubations and 18S rRNA sequencing was chosen to link molecular diversity data of uncultured protists with heterotrophic, presumably bacterivorous, growth. The incubations, conducted with Baltic Sea brackish water, resulted in a consistent shift from a protistan community dominated by phototrophs to one in which heterotrophs predominated. This was determined on the basis of cell abundance and 18S rRNA sequences derived from fingerprint analysis and clone libraries. The bulk of enriched phylotypes after incubation were related to hitherto uncultured marine taxa within chrysophytes, ochrophytes, choanoflagellates, cercozoans, and picobiliphytes, mostly represented in recently established or here defined environmental clades. Their growth in the dark, together with coinciding results from studies with a similar objective, provides evidence that these uncultured taxa represent heterotrophic or mixotrophic species.Conclusions/Significance: These findings shed some light into the trophic role of diverse uncultured protists especially within functionally heterogeneous groups (e.g., chrysophytes, ochrophytes) and groups that appear to be puzzling with regard to their nutrition (picobiliphytes). Additionally, our results indicate that the heterotrophic flagellate community in the southwestern Baltic Sea is dominated by species of marine origin. The combination of unamended incubations with molecular diversity analysis is thus confirmed as a promising approach to explore the trophic mode of environmentally relevant protist taxa for which only sequence data are currently available.