High diversity of the 'Spumella-like' flagellates:: an investigation based on the SSU rRNA gene sequences of isolates from habitats located in six different geographic regions
High diversity of the 'Spumella-like' flagellates:: an investigation based on the SSU rRNA gene sequences of isolates from habitats located in six different geographic regions
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DOI：
10.1111/j.1462-2920.2005.00743.x
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发表时间：
2005-05-01
影响因子：
5.1
通讯作者：
Chatzinotas, A
中科院分区：
文献类型：
--
作者：
Boenigk, J;Pfandl, K;Chatzinotas, A
我们用改良的过滤驯化方法从奥地利、中国、尼泊尔、新西兰、乌干达、肯尼亚、坦桑尼亚和夏威夷的不同淡水和土壤生境中分离到28株类海绵鞭毛虫。在所有样本中都发现了类似海绵的鞭毛虫，并经常是各自环境中的优势食菌鞭毛虫。测定了分离株的小亚基核糖体RNA(SSU RRNA)基因序列，并与已发表的严格金藻属成员序列进行了比对。对这28个新序列的系统发育分析证实了它们在狭义金藻中的位置，并将它们定位在不同的支系中。大多数序列聚在分支C内，并形成几个由绿色分类群相互分隔的亚群，包括属于Ochromonas、Dinobryon、Poterioochromonas等的鞭毛虫。所有土壤分离物与土壤菌株拉长海绵和未被描述的土壤菌株‘Spumella Danica’聚在一起(亚群C1)。水生分离物至少有两个分支(C2和C3)。序列相似性在92%~99.6%之间，类海绵鞭毛虫之间的序列差异高达10%。我们的结论是：(1)类海绵藻鞭毛虫是一个多样性的类群，无论是在菌株间的序列差异还是在基因类型的数量上都是不同的；(2)海绵藻属和Ochromonas属是多系的；(3)基于SSU rRNA基因，即使不同的生态型可能由相同的基因代表，也不能观察到某些分支的生物地理限制。
We isolated 28 strains of 'Spumella-like' flagellates from different freshwater and soil habitats in Austria, People's Republic of China, Nepal, New Zealand, Uganda, Kenya, Tanzania and Hawaii by use of a modified filtration-acclimatization method. 'Spumella-like' flagellates were found in all of the samples and were often among the dominant bacterivorous flagellates in the respective environments. The small subunit ribosomal RNA (SSU rRNA) gene sequence of the isolates was determined and aligned with previously published sequences of members belonging to the Chrysophyceae sensu stricto. Phylogenetic analysis of the 28 new sequences confirmed their position within the Chrysophyceae sensu stricto and positioned them within different clades. Most of the sequences grouped within clade C and formed several subclusters separated from each other by green taxa including flagellates belonging to Ochromonas, Dinobryon, Poterioochromonas and others. All soil isolates clustered together (subcluster C1) with the soil strain Spumella elongata and the undescribed soil strain 'Spumella danica'. Aquatic isolates were affiliated with at least two branches (C2 and C3). Sequence similarity to the closest related member of the Chrysophyceae ranged between 92% and 99.6%, sequence divergence among the 'Spumella-like' flagellates was as high as 10%. We conclude that (i) the 'Spumella-like' flagellates are a diverse group both in terms of sequence dissimilarity between isolates and in terms of the number of genotypes, (ii) Spumella and Ochromonas are polyphyletic, and (iii) based on the SSU rRNA gene no biogeographical restriction of certain branches could be observed even though different ecotypes may be represented by the same genotype.