Jasti Suresh, Sieracki Michael E, Poulton Nicole J, Giewat Michael W, Rooney-Varga Juliette N
Center for Complex Environmental Systems, University of Massachusetts Lowell, 1 University Avenue, Lowell, MA 01854, USA.
Appl Environ Microbiol. 2005 Jul;71(7):3483-94. doi: 10.1128/AEM.71.7.3483-3494.2005.
While several studies have suggested that bacterium-phytoplankton interactions have the potential to dramatically influence harmful algal bloom dynamics, little is known about how bacteria and phytoplankton communities interact at the species composition level. The objective of the current study was to determine whether there are specific associations between diverse phytoplankton and the bacteria that co-occur with them. We determined the phylogenetic diversity of bacterial assemblages associated with 10 Alexandrium strains and representatives of the major taxonomic groups of phytoplankton in the Gulf of Maine. For this analysis we chose xenic phytoplankton cultures that (i) represented a broad taxonomic range, (ii) represented a broad geographic range for Alexandrium spp. isolates, (iii) grew under similar cultivation conditions, (iv) had a minimal length of time since the original isolation, and (v) had been isolated from a vegetative phytoplankton cell. 16S rRNA gene fragments of most Bacteria were amplified from DNA extracted from cultures and were analyzed by denaturing gradient gel electrophoresis and sequencing. A greater number of bacterial species were shared by different Alexandrium cultures, regardless of the geographic origin, than by Alexandrium species and nontoxic phytoplankton from the Gulf of Maine. In particular, members of the Roseobacter clade showed a higher degree of association with Alexandrium than with other bacterial groups, and many sequences matched sequences reported to be associated with other toxic dinoflagellates. These results provide evidence for specificity in bacterium-phytoplankton associations.
虽然多项研究表明，细菌与浮游植物的相互作用有可能极大地影响有害藻华的动态，但对于细菌和浮游植物群落在物种组成水平上如何相互作用，我们知之甚少。本研究的目的是确定不同的浮游植物与其共生细菌之间是否存在特定的关联。我们确定了与缅因湾10株亚历山大藻菌株以及浮游植物主要分类群代表相关的细菌群落的系统发育多样性。为了进行这项分析，我们选择了异养浮游植物培养物，这些培养物：（i）代表广泛的分类范围；（ii）代表亚历山大藻属分离株的广泛地理范围；（iii）在相似的培养条件下生长；（iv）自原始分离以来的时间最短；（v）从营养性浮游植物细胞中分离得到。从培养物中提取的DNA扩增出大多数细菌的16S rRNA基因片段，并通过变性梯度凝胶电泳和测序进行分析。与缅因湾的亚历山大藻物种和无毒浮游植物相比，不同的亚历山大藻培养物（无论地理来源如何）共有更多的细菌物种。特别是，红杆菌属分支的成员与亚历山大藻的关联程度高于与其他细菌类群的关联程度，并且许多序列与报道的与其他有毒甲藻相关的序列相匹配。这些结果为细菌与浮游植物关联中的特异性提供了证据。
