Adaptive strategies by Southern Ocean phytoplankton to lessen iron limitation: Uptake of organically complexed iron and reduced cellular iron requirements
Adaptive strategies by Southern Ocean phytoplankton to lessen iron limitation: Uptake of organically complexed iron and reduced cellular iron requirements
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南大洋浮游植物减少铁限制的适应性策略：吸收有机复合铁并减少细胞铁需求
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发表时间：
2011
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影响因子：
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通讯作者：
P. Boyd
中科院分区：
文献类型：
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作者：
R. Strzepek;M. T. Maldonado;K. Hunter;Russell Frew;P. Boyd
我们报道了低水平铁(Fe)有效性对南大洋硅藻(Fragilariopsis kerguelsis、南极洲真核生物、ProBoscia inmis和南极洲海链藻)和南极洲棕囊藻细胞内Fe浓度和比生长速率的影响的实验室研究结果。所有物种都生长在与铁载体去铁胺B(DFB)络合的铁上。DFB的浓度需要超过铁100倍才能将生长速度限制在≥的50%。南大洋浮游植物也生长在铁的基础上，铁是铁载体铁载体、肠动蛋白或好氧蛋白的10倍过量，而温带沿海硅藻威氏海链藻和假海链藻则不是这样。所有南大洋物种的细胞内Fe浓度和Fe/C比都非常低，并且随着Fe有效性的降低而降低。然而，大型硅藻的细胞体积归一化铁含量和Fe/C比显著低于棕囊藻。短期的铁吸收和胞外Fe(II)产生的测量为棕囊藻具有还原的铁运输途径提供了证据。我们的发现表明，大型硅藻对铁的需求至少比目前报道的海洋藻类物种低2倍，这表明生物还原可能使栖息的浮游植物能够直接利用与强有机配体结合的铁。
We report results of laboratory studies examining the effect of low levels of iron (Fe) availability on the intracellular Fe concentrations and specific growth rates in Southern Ocean diatoms (Fragilariopsis kerguelensis, Eucampia antarctica, Proboscia inermis, and Thalassiosira antarctica) and Phaeocystis antarctica. All species grew on Fe complexed to the siderophore desferrioxamine B (DFB). Concentrations of DFB up to 100‐fold in excess of Fe were required to limit growth rates by ≥ 50%. Southern Ocean phytoplankton also grew on Fe complexed by ≥ 10‐fold excess concentrations of the siderophores ferrichrome, enterobactin, or aerobactin, whereas the temperate coastal diatoms Thalassiosira weissflogii and Thalassiosira pseudonana did not. Intracellular Fe concentrations and Fe : C ratios of all Southern Ocean species were exceptionally low and decreased with decreasing Fe availability. However, large diatoms had significantly lower cell‐volume‐normalized Fe content and Fe : C ratios than Phaeocystis. Short‐term Fe uptake and extracellular Fe(II) production measurements provided evidence that Phaeocystis possesses a reductive Fe transport pathway. Our findings demonstrate that the large‐diatom Fe requirements are at least 2‐fold lower than currently reported for oceanic algal species and suggest that bioreduction may enable resident phytoplankton to directly use Fe bound to strong organic ligands.