Transformation of iodate to iodide in marine phytoplankton driven by cell senescence
Transformation of iodate to iodide in marine phytoplankton driven by cell senescence
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DOI：
10.3354/ab00284
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发表时间：
2010-01-01
期刊：
影响因子：
1.4
通讯作者：
Lochte, K.
中科院分区：
文献类型：
--
作者：
Bluhm, K.;Croot, P.;Lochte, K.
以往的研究表明，由于碘在真光层的出现，浮游植物在碘的生态地球化学循环中起着重要的作用。在培养基中的各种浮游植物类群（硅藻，甲藻和prymnesiophytes）的生长周期的过程中碘的形态变化进行了检查。所有测试的物种都表现出将碘酸盐还原为碘化物的明显能力，尽管不同物种的生产率差异很大（0.01至0.26 nmol l（-1）μ g（-1）chl a d（-1）），其中Eucampia anastritica最小，Pseudo-nitzschia turgiduloides是最有效的碘化物生产者。生产被认为是物种特异性的，与生物量无关（用e表示）。G.细胞大小、细胞体积或叶绿素a含量）。在所有物种中，除了兼养甲藻锥状斯氏藻，碘化物的生产开始在稳定的生长阶段，并在衰老阶段的藻类达到峰值，表明碘化物的生产是连接到细胞衰老。这表明碘酸盐还原是由细胞渗透性增加引起的，我们假设这是由于碘酸盐与从细胞渗出的还原硫物质的后续反应。从衰老到指数生长期的转变导致碘化物的下降，并表明可能发生植脂灵介导的碘化物氧化为碘酸盐。在短时间内保持在黑暗中的健康细胞中无法观察到碘化物的产生。细菌过程似乎只发挥了很小的作用，在碘酸盐的碘化物还原。
Previous studies have suggested that phytoplankton play an important role in the biogeochemical cycling of iodine, due to the appearance of iodide in the euphotic zone. Changes in the speciation of iodine over the course of the growth cycle were examined in culture media for a variety of phytoplankton taxa (diatoms, dinoflagellates and prymnesiophytes). All species tested showed the apparent ability to reduce iodate to iodide, though production rates varied considerably among species (0.01 to 0.26 nmol l(-1) mu g(-1) chl a d(-1)), with Eucampia antarctica the least and Pseudo-nitzschia turgiduloides the most efficient iodide producers. Production was found to be species specific and was not related to biomass (indicated by e. g. cell size, cell volume, or chl a content). In all species, except for the mixotrophic dinoflagellate Scrippsiella trochoidea, iodide production commenced in the stationary growth phase and peaked in the senescent phase of the algae, indicating that iodide production is connected to cell senescence. This suggests that iodate reduction results from increased cell permeability, which we hypothesize is due to subsequent reactions of iodate with reduced sulphur species exuded from the cell. A shift from senescence back to the exponential growth phase resulted in a decline in iodide and indicated that phytoplankton-mediated oxidation of iodide to iodate was likely to be occurring. Iodide production could not be observed in healthy cells kept in the dark for short periods. Bacterial processes appeared to play only a minor role in the reduction of iodate to iodide.