东海原甲藻和链状亚历山大藻对硝酸盐和氨盐的生理响应

Abstract

比较研究了硝酸盐和氨盐培养下,两种甲藻(东海原甲藻(PrOrOCEnTruM dOngHAIEnSE lu)和链状亚历山大藻(AlEXAndrIuMCATEnEllA dH01))对氮营养盐的生理响应.结果表明,两种赤潮生物的最大比增长率均随着培养液中硝酸盐浓度的升高(20~80μMOl/l)而增加,且硝酸盐培养下的最大比增长速率高于同浓度的氨盐,表明在高浓度下,硝酸盐是适宜的氮源.东海原甲藻硝酸还原酶活力(1.14~5.20 fMOl/(CEll.l.MIn))与硝酸盐吸收速率呈正相关,链状亚历山大藻中则未检测到硝酸还原酶活力;两种赤潮生物谷酰氨合成酶活力对硝酸盐和氨盐的响应存在差异,链状亚历山大藻谷氨酰胺合成酶活力(10.93~30.97 PMOl/(CEll.l.MIn))要远高于东海原甲藻(0.34~0.95 PMOl/(CEll.l.MIn)).两种赤潮生物对硝酸盐和氨盐的不同生理响应可能是引起赤潮期间种群更替的一个重要原因.

This study investigated physiological response of Prorocentrum donghaiense Lu and Alexandrium catenella DH01 to nitrate and ammonium.The results showed that the growth rates of P.donghaiense and A.catenella increased with the nitrate concentrations (20～80μmol/L)of the culture medium,and both of them presented higher growth rate in nitrate than in ammonium.In high nutrient concentration,nitrate was regarded as the optimal nitrogen source.The nitrate reductase activity(1.14～5.20 fmol/(cell·L·min))of P.donghaiense exhibited a positive relationship with the nitrate concentrations of the culture medium,while the NR activity of A.catenella could not be detected.The responses of glutamine synthetase in P.donghaiense and A.catenella to nitrate and ammonium was different,and glutamine synthetase activity(10.93～30.97 pmol/(cell.L.min))of A.catenella was higher than that of P.donghaiense(0.34～0.95 pmol/(cell·L·min)).The different physiological responses to nitrate and ammonium between P.donghaiense and A.catenella might be one of the important factors to result in population succession during the process of harmful algal blooms.