球形棕囊藻北部湾株对不同形态磷源的利用及碱性磷酸酶特性研究

【目的】探讨球形棕囊藻(Phaeocystis globosa)北部湾株BBW PG-01对不同磷源利用能力的差异以及碱性磷酸酶(Alkaline phosphatase,AP)特性,揭示溶解有机磷(Dissolved organic phosphorus,DOP)在该藻赤潮发生时的重要作用。【方法】在实验室培养条件下,以KH_2PO_4(PO_4~(3-))、核糖核酸(RNA)、葡萄糖-6-磷酸钠盐(G-6-P)、三磷酸腺苷二钠(ATP)和卵磷脂(LEC)作为磷源,对比研究BBW PG-01在这5种不同磷源培养条件下的生长特征及碱性磷酸酶活性(Alkaline phosphatase activity,APA),并结合磷饥饿条件下的无机磷吸收动力学及碱性磷酸酶动力学分析其对无机磷和有机磷的竞争机制。【结果】5种形态磷源均可被BBW PG-01利用,RNA为其最优生长磷源,而以大分子有机磷LEC为磷源时生长最差,两者最大细胞密度分别为4.40×10~8 cells/L和2.39×10~8 cells/L,水解大分子DOP可能需要更高的酶活性。动力学研究结果表明,在磷缺乏的条件下,BBW PG-01具有通过高亲和力来竞争磷源以维持生长的能力。【结论】球形棕囊藻北部湾株在AP的作用下,能够利用多种DOP进行生长,且在低磷条件下对无机磷(DIP)和DOP均具有较强的竞争能力,海洋中DOP可能是球形棕囊藻赤潮暴发和维持的重要磷源。

Study on the Utilization of Different Phosphorus and Alkaline Phosphatase Characteristics of Phaeocystis globosa Cultivated from Beibu Gulf

Objective] To explore the differences of Phaeocystis globosa BBW PG-01 from Beibu Gulf in utilizing different phosphorus and its characteristic of alkaline phosphatase (AP) can reveal the important role that DOP played when the algae bloom occurs.Methods] Under laboratory culture condition and taking KH₂PO₄ (PO₄^3-), RNA, Glucose 6 phosphate (G-6-P), adenosine triphosphate (ATP) and lecithin (LEC) as phosphorus sources, the growth characteristics and Alkaline phosphatase activity (APA) of BBW PG-01 in these five different phosphorus sources were compared.Combining the inorganic phosphorus absorption kinetics and alkaline phosphatase kinetics under phosphorus starvation, the competitive mechanism of inorganic phosphorus and organic phosphorus was analyzed.Results] It was found that five morphological phosphorus sources could be utilized by BBW PG-01.RNA was the optimal source of phosphorus for its growth, however, with macromolecular organic phosphorus LEC as the phosphorus source, the growth was the worst.The maximum cell density for these two sources was 4.40×10⁸ cells/L and 2.39×10⁸ cells/L, hydrolysis of macromolecules DOP might require higher enzyme activity.Kinetic studies indicated that BBW PG-01 had the ability to compete for phosphorus sources to sustain growth with high affinity in the deficiency of phosphorus.Conclusion] Under the action of AP, Phaeocystis globosa from Beibu Gulf could grow with many kinds of DOPs and had strong competitive ability to both DIP and DOP under low phosphorus conditions.DOP in the ocean might be an important phosphorus source for the outbreak and maintenance of Phaeocystis globosa red tide.