Variations in the buoyancy response of Microcystis aeruginosa to nitrogen, phosphorus and light
Variations in the buoyancy response of Microcystis aeruginosa to nitrogen, phosphorus and light
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DOI：
10.1093/plankt/23.12.1399
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发表时间：
2001-12-01
影响因子：
2.1
通讯作者：
Ganf, GG
中科院分区：
文献类型：
--
作者：
Brookes, JD;Ganf, GG
铜绿微囊藻对光的反应表现出一系列浮力变化，这取决于细胞先前的营养或光历史。对光的短期浮力反应嵌套在一段时间内的长期反应中，因为蓝细菌对其营养和光气候做出反应，这可能体现在它们的气泡体积、光合速率和碳水化合物代谢中。在暴露于饱和辐照度之前，铜绿微囊藻培养物经过一系列氮 (N)、磷 (P) 或光预处理，这些结果用于说明群体可以根据营养和光照条件的细微变化表现出一系列浮力反应。 N-limited (0 muM) 细胞的气体囊泡体积稀释，碳水化合物含量增加，导致浮力损失。 10 μM N 中的细胞在光照过程中其气体囊泡含量增加；然而，随着碳水化合物的增加，这不足以维持大多数细胞的浮力。 100 μM N 中的细胞增加了气泡体积，比限氮处理更有效地代谢碳水化合物，并保留了正浮力。在光照过程中，0 muM P 预处理的细胞浮力变化很小，尽管气泡体积稀释且碳水化合物增加。在0.5 muM P预处理的细胞中，漂浮的个体比例没有变化，尽管气泡体积和碳水化合物增加。 10 muM P 预处理的细胞在光照期间气泡体积显着增加，并且由于碳水化合物积累而导致一些浮力损失。在测试的光强度范围内生长的细胞在 24 小时光处理期间其气泡体积均增加。对于所有三种光预处理，气体囊泡的实际产生率是相同的；然而，生长依赖性稀释率是由先前的光历史决定的，这导致每个细胞的相对气体囊泡体积不同。在光照期间，每个细胞的碳水化合物增加最小，但所有处理都显示出经典的浮力损失反应。
Microcystis aeruginosa displays a range of variability in buoyancy in response to light which is dependent upon the previous nutrient or light history of the cell. The short-term buoyancy response to light is nested into a longer term response, over a period of days, as cyanobacteria respond to their nutrient and light climate, which may be manifested in their gas vesicle volume, photosynthetic rate and carbohydrate metabolism. Microcystis aeruginosa cultures were subjected to a range of nitrogen (N), phosphorus (P) or light pre-treatments before exposure to saturating irradiance, and these results are used to illustrate that populations can display a range of buoyancy responses dependent upon subtle changes in nutrient and light conditions. N-limited (0 muM) cells suffered a dilution in gas vesicle volume and increased carbohydrate content, which resulted in a loss of buoyancy. Cells in 10 muM N increased their gas vesicle content during light exposure; however, this was insufficient to maintain buoyancy in the majority of cells as carbohydrate increased. Cells in 100 muM N increased their gas vesicle volume, metabolized carbohydrate more efficiently than the N-limited treatments and retained positive buoyancy. During light exposure, there was minimal change in buoyancy in 0 muM P pre-treated cells, although there was a dilution in gas vesicle volume and an increase in carbohydrate. In 0.5 muM P pre-treated cells, the proportion of individuals floating did not change, although gas vesicle volume and carbohydrate increased. There was a significant increase in gas vesicle volume in 10 muM P pre-treated cells during light exposure, and some buoyancy loss due to carbohydrate accumulation. Cells grown in the range of light intensities tested all increased their gas vesicle volume during the 24 h light treatment. The actual rate of gas vesicle production was equivalent for all three light pretreatments; however, the growth-dependent dilution rate was determined by the previous light history, which resulted in different relative gas vesicle volume per cell. There was minimal increase in carbohydrate per cell during the light period, yet all treatments displayed the classical buoyancy loss response.