Dominant oceanic bacteria secure phosphate using a large extracellular buffer.
Dominant oceanic bacteria secure phosphate using a large extracellular buffer.
复制标题
DOI：
10.1038/ncomms8878
复制
发表时间：
2015-07-22
影响因子：
16.6
通讯作者：
Scanlan DJ
中科院分区：
文献类型：
--
作者：
Zubkov MV;Martin AP;Hartmann M;Grob C;Scanlan DJ
无处不在的SAR11和原氯球细菌设法在北大西洋亚热带环流的磷酸盐贫乏的表层水域维持了充足的磷酸盐供应。此外，似乎与直觉相反的是，它们对磷的吸收在更多产的热带水域更低，就好像它们对磷的细胞需求在那里减少了一样。通过对33P-磷酸盐脉冲32P-磷酸盐追逐细胞的流动分选，我们证明了原氯球菌和SAR11细胞都利用了高达复制其染色体所需磷酸盐数量5-40倍的不稳定磷酸盐的细胞外缓冲区。数学模型证实了这一结论。缓冲液越满，细胞吸收磷酸盐的速度就越慢，以至于在磷酸盐充足的热带水域，细胞可以饱和它们的缓冲液，它们的磷酸盐吸收变得微不足道。因此，缓冲存储是SAR11和原氯球菌的一种通用的、确保生长的适应，这些细菌缺乏内部储备来减少它们对生物可用环境磷酸盐的依赖。海洋SAR11α蛋白细菌和原氯球藻蓝细菌在磷酸盐贫乏的地区大量存在，尽管它们对生长至关重要。在这里，Zubkov等人。表明这些浮游细菌利用细胞外不稳定磷的缓冲来减少它们对环境中可生物利用的磷的依赖。
The ubiquitous SAR11 and Prochlorococcus bacteria manage to maintain a sufficient supply of phosphate in phosphate-poor surface waters of the North Atlantic subtropical gyre. Furthermore, it seems that their phosphate uptake may counter-intuitively be lower in more productive tropical waters, as if their cellular demand for phosphate decreases there. By flow sorting 33P-phosphate-pulsed 32P-phosphate-chased cells, we demonstrate that both Prochlorococcus and SAR11 cells exploit an extracellular buffer of labile phosphate up to 5–40 times larger than the amount of phosphate required to replicate their chromosomes. Mathematical modelling is shown to support this conclusion. The fuller the buffer the slower the cellular uptake of phosphate, to the point that in phosphate-replete tropical waters, cells can saturate their buffer and their phosphate uptake becomes marginal. Hence, buffer stocking is a generic, growth-securing adaptation for SAR11 and Prochlorococcus bacteria, which lack internal reserves to reduce their dependency on bioavailable ambient phosphate. Oceanic SAR11 Alphaproteobacteria and Prochlorococcus cyanobacteria are abundant in phosphate-poor regions, despite it being vital for growth. Here, Zubkov et al. show these bacterioplankton exploit an extracellular buffer of labile phosphate to reduce their dependency on bioavailable ambient phosphate.