Comparative effects of ammonium, nitrate and urea on growth and photosynthetic efficiency of three bloom-forming cyanobacteria
Comparative effects of ammonium, nitrate and urea on growth and photosynthetic efficiency of three bloom-forming cyanobacteria
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DOI：
10.1111/fwb.13099
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发表时间：
2018-07-01
影响因子：
2.7
通讯作者：
Trick, Charles G.
中科院分区：
文献类型：
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作者：
Erratt, Kevin J.;Creed, Irena F.;Trick, Charles G.
1.在过去的半个世纪里，尿素肥料越来越受欢迎，现在是应用于农业景观的主要氮（N）形式。尿素肥料的广泛使用有利于其出口到当地的水道，尿素污染可能有助于蓝藻有害藻华在淡水沃茨的繁殖和维持。蓝藻响应尿素和无机氮添加的相对成功进行了研究，以了解是否最近的变化的幅度和组成的N负载创造了一个场景，现在有利于蓝藻在淡水沃茨的优势。2.以硝酸盐（NO3）、铵（NH4）和尿素（CO（NH2）2）为氮源，研究了3种水华蓝藻（微囊藻、长籽藻和聚球藻）的生长和光合效率。我们假设，N基板，需要最低的能量投资或提供最高的能量回报将有利于最佳的生长和光合性能。我们预测，相对于NHthorn4或NO3，尿素将导致更高的细胞生长和色素产生，因为尿素提供两倍的N量和额外的碳（C）源，使其能量效率更高。3.蓝藻生物量没有显着提高尿素相对于无机氮的形式。尿素上的生长匹配NO 3为所有物种，而生长NHthorn4相比尿素或NO 3减半。然而，蓝藻细胞有较高的色素浓度时，生长在尿素相对于无机N源。这些研究结果表明，尿素水解提供的额外营养成分并不直接用于活跃的生长，而是在次级池中积累，以增加富含Nrich的化合物，如色素的产生。4.虽然尿素没有影响蓝藻数量"（i。e.与无机氮源相比，它通过增强色素合成产生更高"质量"的细胞，并可能在光限制条件下赋予蓝藻竞争优势。此外，当供应过量时，蓝藻迅速消耗超过其生物合成需求的尿素，这表明一种形式的尿素"暴食"。"这些结果证明了氮形态对蓝藻生理反应的重要性，并加强了尿素和内陆沃茨蓝藻有害藻华之间的联系。
1. Urea-based fertilisers have grown in popularity over the past half-century and are now the dominant nitrogen (N) form applied to agricultural landscapes. The widespread use of urea fertilisers has favoured its export to local waterways, and urea pollution may be contributing to the propagation and maintenance of cyanobacteria harmful algal blooms in fresh waters. The relative success of cyanobacteria in response to urea and inorganic N additions was studied to understand whether the recent changes in the magnitude and composition of N loading have created a scenario that now favours the dominance of cyanobacteria in fresh waters. 2. Growth and photosynthetic efficiency of three bloom-forming freshwater cyanobacteria (Microcystis, Dolichospermum and Synechococcus) grown on nitrate (NO 3), ammonium (NHthorn4) and urea (CO(NH2) 2) as the sole N form were monitored. We hypothesised that N substrates that require the lowest energetic investment or offer the highest energetic return would favour optimal growth and photosynthetic performance. We predicted that urea would result in higher cellular growth and pigment production relative to NHthorn4 or NO 3, as urea provides twice the amount N and an additional carbon (C) source making it more energetically efficient. 3. Cyanobacteria biomass was not significantly enhanced on urea relative to inorganic N forms. Growth on urea was matched by NO 3 for all species, whereas growth on NHthorn4 was halved compared urea or NO 3. However, cyanobacteria cells had higher pigment concentrations when grown on urea relative to inorganic N sources. These findings suggest that the additional nutrient building blocks supplied from the hydrolysis of urea were not directed towards active growth, but rather accumulated in secondary pools to increase production of Nrich compounds, such as pigments. 4. Although urea did not influence cyanobacteria quantity "(i. e. biomass)" compared to inorganic N sources, it produced higher " quality" cells by enhancing pigment synthesis and potentially giving cyanobacteria a competitive advantage in lightlimiting conditions. Furthermore, when supplied in excess, cyanobacteria rapidly consumed urea in excess of their biosynthetic requirements suggesting a form of urea " gluttony." These results demonstrate the importance of N speciation on cyanobacteria physiological responses and reinforce the emerging links between urea and cyanobacteria harmful algal blooms in inland waters.