链状亚历山大藻(东海株)对磷营养物质的需求与吸收策略

针对长江口临近海域富营养化特征,设计实验研究了链状亚历山大藻(东海株ACDH)生长的最适N/P、对PO4-P的吸收能力,以及对有机磷营养物质的利用能力,分析了ACDH藻株对P营养物质的需求和吸收策略.结果表明,ACDH藻株生长的最适N/P在9～11,其生长需要相对较多的P.ACDH藻株对PO4-P的最大吸收速率(Vm)和半饱和常数(Ks)分别为0.23 pmol/cell·h和0.92 μmol/L,能够吸收较低浓度的PO4-P,但与该海域典型赤潮藻种中肋骨条藻相比,对低浓度PO4-P的竞争不占优势.ACDH藻株在PO4-P限制下具有强烈的碱性磷酸酶表达,有可能通过碱性磷酸酶利用有机磷营养物质,这在其赤潮的形成中应具有重要作用.

Demand and adsorption strategies of phosphorus of Alexandrium catenella isolated from East China Sea

The experiments were designed, using a strain (ACDH) of Alexandrium catenella isolated in the East China Sea, for studying its optimal N∶ P ratio, phosphate uptake characteristics, and the ability of utilization of organic phosphorus compounds. The results showed that the optimal N∶ P ratio of strain ACDH is about 9 to 11, which is much lower than the ratio of nitrate to phosphate in adjacent sea areas in the Changjiang Estuary. The maximum uptake rate (Vm) and half saturation concentration (Ks) of strain ACDH for phosphate are 0.23 pmol/cell.h and 0.92 mol/L, respectively. Compared to Skeletonema constatum, a popular red tide causative species in the East China Sea, strain ACDH is not very competitive in utilization of low-concentration phosphate in seawater. Alkaline phosphatase activity could be detected in cells of strain ACDH under P limitation condition, suggesting that strain ACDH could utilize the organic forms of phosphorus compounds. The ability in utilizing organic phosphorus compounds could be an important mechanism for the occurrence of A. catenella blooms in this area.