Iron limitation effects on nitrogen-fixing organisms with possible implications for cyanobacterial blooms
Iron limitation effects on nitrogen-fixing organisms with possible implications for cyanobacterial blooms
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DOI：
10.1093/femsec/fiy046
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发表时间：
2018-05-01
影响因子：
4.2
通讯作者：
Passy, Sophia I.
中科院分区：
文献类型：
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作者：
Larson, Chad A.;Mirza, Babur;Passy, Sophia I.
以蓝细菌为主的有害藻华现象正在增加。许多有助于这些水华的类群能够固定大气中的氮，在氮可用性低的条件下应该受到青睐。然而，合成固氮酶（负责固氮的酶）在能量上是昂贵的，并且需要大量的铁浓度。除磷氮贫流应促进固氮，但迄今为止的实验结果还没有定论，这表明其他因素可能参与控制这一过程。由于铁在许多溪流中可能受到限制，我们研究了磷-铁共沉淀对固氮生物群落结构的影响。在溪流微观世界中，使用微观和分子序列数据，我们观察到：（i）在高磷和铁的低氮处理中，形成固氮蓝藻的异形胞的丰度最大，（ii）非光合氮的丰度更大-在有氮和无氮的处理中，我们还发现，分子结果与显微鉴定结果的比较，关于蓝藻群落的补充信息。我们的调查表明，潜在的磷-铁共模拟流固氮生物。
Cyanobacteria-dominated harmful algal blooms are increasing in occurrence. Many of the taxa contributing to these blooms are capable of fixing atmospheric nitrogen and should be favored under conditions of low nitrogen availability. Yet, synthesizing nitrogenase, the enzyme responsible for nitrogen fixation, is energetically expensive and requires substantial concentrations of iron. Phosphorus addition to nitrogen poor streams should promote nitrogen fixation, but experimental results so far have been inconclusive, suggesting that other factors may be involved in controlling this process. With iron potentially limited in many streams, we examined the influence of phosphorus-iron colimitation on the community structure of nitrogen-fixing organisms. In stream microcosms, using microscopic and molecular sequence data, we observed: (i) the greatest abundance of heterocyst forming nitrogen-fixing cyanobacteria in low nitrogen treatments with high phosphorus and iron and (ii) greater abundance of non-photosynthetic nitrogen-fixing bacteria in treatments with nitrogen compared to those without it. We also found that comparisons between molecular results and those obtained from microscopic identification provided complementary information about cyanobacterial communities. Our investigation indicates the potential for phosphorus-iron colimitation of stream nitrogen-fixing organisms.