Lynn Scott G, Kilham Susan S, Kreeger Daniel A, Interlandi Sebastian J
Department of Bioscience and Biotechnology, Drexel University, Philadelphia, Pennsylvania 19104School of Environmental Science, Engineering and Policy, Drexel University, Philadelphia, Pennsylvania 19104Academy of Natural Sciences Philadelphia, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania 19103School of Environmental Science, Engineering and Policy, Drexel University, Philadelphia, Pennsylvania 19104.
J Phycol. 2000 Jun;36(3):510-522. doi: 10.1046/j.1529-8817.2000.98251.x. Epub 2001 Dec 25.
The objective of this study was to examine the differences in the biochemical and elemental stoichiometry of a freshwater centric diatom, Stephanodiscus minutulus (Grun.), under various nutrient regimes. Stephanodiscus minutulus was grown at μ or 22% of μ under limitation by silicon, nitrogen, or phosphorus. Cell sizes for nutrient-limited cultures were significantly smaller than the non-limited cell sizes, with N-limited cells being significantly smaller than all other treatments. Compared with the nutrient-replete treatment, both carbohydrates and lipids increased in Si- and P-limited cells, whereas carbohydrates increased but proteins decreased in N-limited cells. All of the growth-limited cells showed an increase of carbohydrate and triglyceride, and a decrease of cell size and polar lipids as a percentage of total lipids. The non-limited cells also had a significantly higher chl a concentration and galactolipids as a percentage of total lipids than any of the limited treatments, and the low-Si and low-P cells had significantly higher values than the low-N cells. The particulate C concentrations showed significant differences between treatments, with the Si- and P-limited treatments being significantly higher than the N- and non-limited treatments. Particulate Si did not show a strong relationship with any of the parameters measured, and it was the only parameter with no differences between treatments. The low-Si cells had a significantly higher P content (about two times more) than any other treatment, presumably owing to the luxury consumption of P, and a correspondingly high phospholipid concentration. The elemental data showed that S. minutulus had a high P demand with low optimum N:P (4) and Si:P (10) ratios and a C:N:P ratio of 109:16:2.3. The particulate C showed a positive relationship with POM (r = 0.93), dry weight (r = 0.88), lipid (r = 0.87) and protein (r = 0.84, all P < 0.0001). Particulate N showed a positive relationship with galactolipids (r = 0.95), protein (r = 0.90), dry weight (r = 0.78), lipid (r = 0.75), and cell volume (r = 0.64, all P < 0.0001). It is evident that nutrient limitation in the freshwater diatom S. minutulus has pronounced effects on its biochemical and elemental stoichiometry.
本研究的目的是考察淡水中心硅藻小环藻（Stephanodiscus minutulus (Grun.)）在不同营养条件下的生化和元素化学计量差异。小环藻在硅、氮或磷限制下，以μ或μ的22%的生长速率培养。营养限制培养的细胞大小显著小于非限制细胞大小，其中氮限制细胞显著小于所有其他处理组。与营养充足处理相比，硅和磷限制的细胞中碳水化合物和脂质均增加，而氮限制的细胞中碳水化合物增加但蛋白质减少。所有生长受限的细胞均表现出碳水化合物和甘油三酯增加，细胞大小和极性脂质占总脂质的百分比降低。非限制细胞的叶绿素a浓度和半乳糖脂占总脂质的百分比也显著高于任何限制处理组，低硅和低磷细胞的值显著高于低氮细胞。颗粒碳浓度在处理组间存在显著差异，硅和磷限制处理组显著高于氮和非限制处理组。颗粒硅与所测任何参数均无强相关性，且是处理组间无差异的唯一参数。低硅细胞的磷含量（约为其他处理组的两倍）显著高于其他处理组，可能是由于磷的奢侈消耗，且磷脂浓度相应较高。元素数据表明，小环藻对磷的需求较高，最佳氮磷比（4）和硅磷比（10）较低，碳氮磷比为109:16:2.3。颗粒碳与颗粒有机物质（r = 0.93）、干重（r = 0.88）、脂质（r = 0.87）和蛋白质（r = 0.84，所有P < 0.0001）呈正相关。颗粒氮与半乳糖脂（r = 0.95）蛋白质（r = 0.90）、干重（r = 0.78）、脂质（r = 0.75）和细胞体积（r = 0.64，所有P < 0.0001）呈正相关。显然，淡水硅藻小环藻中的营养限制对其生化和元素化学计量有显著影响。
