Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta, 37-49, 08003, Barcelona, Catalonia, Spain,
Microb Ecol. 2013 Oct;66(3):489-99. doi: 10.1007/s00248-013-0251-y. Epub 2013 Jun 11.
The diversity of heterotrophic flagellates is generally based on cultivated strains, on which ultrastructural, physiological, and molecular studies have been performed. However, the relevance of these cultured strains as models of the dominant heterotrophic flagellates in the marine planktonic environment is unclear. In fact, molecular surveys typically recover novel eukaryotic lineages that have refused cultivation so far. This study was designed to directly address the culturing bias in planktonic marine heterotrophic flagellates. Several microcosms were established adding increasing amounts and sources of organic matter to a confined natural microbial community pre-filtered by 3 μm. Growth dynamics were followed by epifluorescence microscopy and showed the expected higher yield of bacteria and heterotrophic flagellates at increased organic matter additions. Moreover, protist diversity analyzed by molecular tools showed a clear substitution in the community, which differed more and more from the initial sample as the organic matter increased. Within this gradient, there was also an increase of sequences related to cultured organisms as well as a decrease in diversity. Culturing bias is partly explained by the use of organic matter in the isolation process, which drives a shift in the community to conditions closer to laboratory cultures. An intensive culturing effort using alternative isolation methods is necessary to allow the access to the missing heterotrophic flagellates that constitute the abundant and active taxa in marine systems.
异养鞭毛虫的多样性通常基于培养菌株，这些菌株已经进行了超微结构、生理和分子研究。然而，这些培养菌株作为海洋浮游环境中优势异养鞭毛虫模型的相关性尚不清楚。事实上，分子调查通常会发现迄今为止拒绝培养的新的真核生物谱系。本研究旨在直接解决浮游海洋异养鞭毛虫培养中的偏倚问题。通过在预先用 3 μm 过滤的受限自然微生物群落中添加越来越多的有机物和来源，建立了几个微宇宙。通过荧光显微镜观察生长动态，结果表明随着有机物的增加，细菌和异养鞭毛虫的产量预期更高。此外，通过分子工具分析的原生生物多样性显示出群落的明显替代，随着有机物的增加，群落与初始样本的差异越来越大。在这个梯度中，与培养生物有关的序列也有所增加，多样性有所下降。培养偏倚部分归因于分离过程中有机物的使用，这导致群落向更接近实验室培养的条件转变。需要进行密集的培养工作，采用替代的分离方法，以允许获得构成海洋系统中丰富和活跃类群的缺失异养鞭毛虫。
