Garcia Nathan S, Sexton Julie, Riggins Tracey, Brown Jeff, Lomas Michael W, Martiny Adam C
Department of Earth System Science, University of California, Irvine, Irvine, CA, United States.
Bigelow Laboratory for Ocean Sciences, National Center for Marine Algae and Microbiota, East Boothbay, ME, United States.
Front Microbiol. 2018 Mar 27;9:543. doi: 10.3389/fmicb.2018.00543. eCollection 2018.
Current hypotheses suggest that cellular elemental stoichiometry of marine eukaryotic phytoplankton such as the ratios of cellular carbon:nitrogen:phosphorus (C:N:P) vary between phylogenetic groups. To investigate how phylogenetic structure, cell volume, growth rate, and temperature interact to affect the cellular elemental stoichiometry of marine eukaryotic phytoplankton, we examined the C:N:P composition in 30 isolates across 7 classes of marine phytoplankton that were grown with a sufficient supply of nutrients and nitrate as the nitrogen source. The isolates covered a wide range in cell volume (5 orders of magnitude), growth rate (<0.01-0.9 d), and habitat temperature (2-24°C). Our analysis indicates that C:N:P is highly variable, with statistical model residuals accounting for over half of the total variance and no relationship between phylogeny and elemental stoichiometry. Furthermore, our data indicated that variability in C:P, N:P, and C:N within Bacillariophyceae (diatoms) was as high as that among all of the isolates that we examined. In addition, a linear statistical model identified a positive relationship between diatom cell volume and C:P and N:P. Among all of the isolates that we examined, the statistical model identified temperature as a significant factor, consistent with the temperature-dependent translation efficiency model, but temperature only explained 5% of the total statistical model variance. While some of our results support data from previous field studies, the high variability of elemental ratios within Bacillariophyceae contradicts previous work that suggests that this cosmopolitan group of microalgae has consistently low C:P and N:P ratios in comparison with other groups.
当前的假说认为，海洋真核浮游植物的细胞元素化学计量，如细胞碳：氮：磷（C:N:P）的比率，在系统发育类群之间存在差异。为了研究系统发育结构、细胞体积、生长速率和温度如何相互作用以影响海洋真核浮游植物的细胞元素化学计量，我们检测了7类海洋浮游植物中30个分离株的C:N:P组成，这些分离株在营养物质充足且以硝酸盐作为氮源的条件下生长。这些分离株的细胞体积（跨越5个数量级）、生长速率（<0.01 - 0.9 d⁻¹）和栖息地温度（2 - 24°C）范围广泛。我们的分析表明，C:N:P具有高度变异性，统计模型残差占总方差的一半以上，且系统发育与元素化学计量之间没有关系。此外，我们的数据表明，硅藻门（硅藻）内C:P、N:P和C:N的变异性与我们检测的所有分离株之间的变异性一样高。另外，一个线性统计模型确定了硅藻细胞体积与C:P和N:P之间存在正相关关系。在我们检测的所有分离株中，统计模型确定温度是一个显著因素，这与温度依赖性翻译效率模型一致，但温度仅解释了总统计模型方差的5%。虽然我们的一些结果支持了先前野外研究的数据，但硅藻门内元素比率的高变异性与先前的研究结果相矛盾，先前的研究表明，与其他类群相比，这个世界性的微藻类群的C:P和N:P比率一直较低。
