Seasonal dynamics of SAR11 populations in the euphotic and mesopelagic zones of the northwestern Sargasso Sea
Seasonal dynamics of SAR11 populations in the euphotic and mesopelagic zones of the northwestern Sargasso Sea
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DOI：
10.1038/ismej.2008.117
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发表时间：
2009-03-01
期刊：
影响因子：
11
通讯作者：
Vergin, Kevin
中科院分区：
文献类型：
--
作者：
Carlson, Craig A.;Morris, Robert;Vergin, Kevin
2003 年至 2005 年，在百慕大大西洋时间序列研究 (BATS) 地点，通过荧光原位杂交 (FISH) 对表面 300 m 八个深度的浮游细菌进行了计数。SAR11 是寡营养系统中的优势异养生物；因此，解决它们的时间动态可以为有机和无机营养物的循环提供重要的见解。该定量时间序列数据揭示了亮光区 (0-120) 和中层上部 (160-300 m) 区域 SAR11 丰度的独特年度分布模式，这些模式与水体的季节性混合和分层可重复相关。将 BATS 采集的十年样本生成的末端限制性片段长度多态性 (T-RFLP) 数据与 FISH 数据相结合，对 SAR11 分支种群的年度动态进行建模。构建16S rRNA基因克隆文库，验证T-RFLP数据与SAR11进化枝结构的相关性。在三种 SAR11 生态型的优势中观察到明显的垂直和时间转变。导致不同 SAR11 种群之间变化的机制尚不清楚，但可能是精细调整的生理适应的结果，这些适应沿着生态系统中的物理和化学梯度划分种群。我们描述的进化血统与时间/空间模式之间的相关性证实了至少三种 SAR11 生态型占据了马尾藻海表层，并揭示了其种群动态的新细节。
Bacterioplankton belonging to the SAR11 clade of alpha-proteobacteria were counted by fluorescence in situ hybridization (FISH) over eight depths in the surface 300m at the Bermuda Atlantic Time-series Study (BATS) site from 2003 to 2005. SAR11 are dominant heterotrophs in oligotrophic systems; thus, resolving their temporal dynamics can provide important insights to the cycling of organic and inorganic nutrients. This quantitative time-series data revealed distinct annual distribution patterns of SAR11 abundance in the euphotic (0-120) and upper mesopelagic (160-300 m) zones that were reproducibly correlated with seasonal mixing and stratification of the water column. Terminal restriction fragment length polymorphism (T-RFLP) data generated from a decade of samples collected at BATS were combined with the FISH data to model the annual dynamics of SAR11 subclade populations. 16S rRNA gene clone libraries were constructed to verify the correlation of the T-RFLP data with SAR11 clade structure. Clear vertical and temporal transitions were observed in the dominance of three SAR11 ecotypes. The mechanisms that lead to shifts between the different SAR11 populations are not well understood, but are probably a consequence of finely tuned physiological adaptations that partition the populations along physical and chemical gradients in the ecosystem. The correlation between evolutionary descent and temporal/spatial patterns we describe, confirmed that a minimum of three SAR11 ecotypes occupy the Sargasso Sea surface layer, and revealed new details of their population dynamics.