| 摘要: |
| 于1991年11月在胶州湾采集尖刺拟菱形藻，以毛细管法分离纯化，建立克隆藻株，以此为实验材料，研究其在营养盐饥饿状态下对NO3-N，NH4-N和PO4-P的吸收动力学及在营养盐限制下的增殖特征。结果表明；在营养盐饥饿状态下，该藻对NO3-N，NH4-N和PO4-P的吸收过程符合米氏方程，半饱和常数（Ks）分别为2.29，2.18和1.40 μmol/L。最大吸收速率（Vm）分别为7.28，18.90，1.48×10-13 mol/(cell?h)。在营养盐限制下，该藻的比生长率与限制性营养元素细胞含量之间的关系符合Droop方程。求得该藻氮限制下的最大比生长率为1.45d-1，最小细胞氮含量为6.30×10-13 mol/cell;磷限制下的最大比生长率为1.37d-1，最小细胞磷含量为0.69×10-13 mol/cell。根据以上结果，计算出该藻对NO3-N，NH4-N和PO4-P的比最大吸收速率分别为28，72和51d-1。研究说明，该藻具有较强的吸收氮的能力，而吸收磷的能力较弱，推测磷可能是自然环境中限制其生长的营养因子。 |
| 关键词: 尖刺拟菱形藻 营养盐吸收 动力学 营养盐限制 增殖 |
| DOI： |
| 分类号: |
| 基金项目:国家攀登计划B资助!B6-07-02 |
附件 |
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| NUTRIENT UPTAKE KINETICS AND GROWTH UNDER NUTRIENT LIMITATION OF PSEUDONITZSCHIA |
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Zhang Cheng, Zou Jingzhong
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Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071
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| Abstract: |
| Pseudonitzschia pungens was collected from the Jiaozhou Bay using a Shallow Water Type III plankton net (with mesh size of ca. 65μm) in November 1991. A clonal culture was established using micro-pipette method, subsequently; this was applied in this study. This culture was grown in f/2 media at ca. 20°C with salinity of 32, light intensity of ca. 5000lx, and light:dark cycle of 14:10. Nitrogen- or phosphorous-starved cells of the species were obtained by growing the cells in f/2 media without addition of nitrogen or phosphorous until the ambient nitrogen or phosphorous had been depleted for 3 days. Such cells were used to study its uptake kinetics of NO3-N, NH4-N and PO4-P. In the NO3-N uptake experiments, the concentrations of l, 2, 4, 6, 8, and 10 μmol/L were used. The same concentrations were adopted in the NH4-N uptake experiments. The concentrations used for the PO3-P uptake experiments were 0.5, 1, 2, 4, 6, and 8 μmol/L. The uptake rates were represented by the disappearing rates of the targeting nutrients. Semi-continuous culture mode was employed to examine the growth characteristics under the controlled nitrogen or phosphorous conditions. Five dilution rates were employed, ranging between 0.05, 0.10, 0.20, 0.30, and 0.40. The concentrations of the limiting nitrogen and phosphorous in these experiments were 5 and 2 μmol/L, respectively. The results show that in nutrient uptake experiments, the nutrient uptake rates (v) are constant within the experiment periods (0 to 60 min) and the nutrient uptake kinetics can be described by the Michaelis-Menton equation: v = Vm*s/(Ks+s). The half-saturation constants (Ks) for NO3-N, NH4-N and PO4-P are 2.29, 2.18, and 1.40 μmol/L, respectively. Under the experimental conditions, maximal uptake rates (Vm) for NO3-N, NH4-N and PO4-P are 7.28, 18.90, and 1.48×10-13 mol/cell, respectively. In the semi-continuous culture experiments, the relationship between steady state specific growth rates (μ) and cell quotas of the limited nutrient elements (q) follows the Droop equation: μ = μm(1-q/q0). Maximal growth rates μm and minimum cell quota q0 associated with the limited nitrogen concentrations are 1.45d-1 and 6.30×10-13 mol/cell respectively; those associated with the limited phosphorous concentrations were l.37d-1 and 0.69×10-13 mol/cell, respectively. On the basis of the results obtained from the nutrient uptake experiments and the nutrient limited growth experiments of P. pungens, the specific maximal uptake rates for NO3-N, NH4-N and PO4-P of this species are 28, 72, and 51d-1 respectively. Compared with the data of other phytoplanktonic species, P. pungens shows a high ability to uptake inorganic nitrogen, and a relatively low ability to uptake inorganic phosphorous. Therefore, phosphorous might be the controlling nutrient of this species in the natural environment. |
| Key words: Pseudonilzschia pungens, Nutrient uptake, Kinetics, Nutrient limitation growth |
