球形棕囊藻对不同氮源的吸收利用机制  

ABSORPTION AND UTILIZATION OF DIFFERENT NITROGEN SOURCES BY PHAEOCYSTIS GLOBOSA

作　　者：蒙蕊 宋秀贤[1,2,3] 刘淑雅 姜文彬 俞志明 MENG Rui;SONG Xiu-Xian;LIU Shu-Ya;JIANG Wen-Bin;YU Zhi-Ming(CAS Key Laboratory of Marine Ecology and Environmental Sciences,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China;Laboratory of Marine Ecology and Environmental Science,Qingdao National Laboratory for Marine Science and Teehnology,Qingdao 266071,China;University of Chinese Academy of Sciences,Beij＇ing 100049,China)

机构地区：[1]中国科学院海洋生态与环境科学重点实验室(中国科学院海洋研究所),青岛266071 [2]青岛海洋科学与技术国家实验室海洋生态与环境科学功能实验室,青岛266071 [3]中国科学院大学,北京100049

出　　处：《海洋与湖沼》2018年第4期802-808,共7页Oceanologia Et Limnologia Sinica

基　　金：国家重点研发计划;2017YFC1404300号;鳌山科技创新计划项目"近海生态灾害发生机理与防控策略";2016ASKJ02-3号;青岛海洋科学与技术国家实验室鳌山人才计划资助;2017ASTCP-OS16号

摘　　要：本文以球形棕囊藻为实验材料,从营养盐利用及生理生化角度研究了不同氮源对其生长的影响。研究结果表明:球形棕囊藻以尿素为氮源的藻密度以及叶绿素a浓度均高于以NH_4Cl或NaNO_3为氮源的藻密度以及叶绿素a浓度;硝酸盐还原酶(NR)及脲酶(urease)活性表达受培养基中氮源浓度及吸收速率调控,硝酸盐还原酶在以NaNO_3为氮源条件下活性最高,脲酶在以尿素为氮源条件下活性表达最强;通过比较不同条件下硝酸盐还原酶活性及脲酶活性,发现脲酶活性远高于硝酸盐还原酶活性,这可能是以尿素为氮源条件下球形棕囊藻藻密度更高的主要原因。研究还发现,氮饥饿状态的球形棕囊藻对NH_4^+具有很高的初始吸收速率,8h左右将NH_4^+快速吸收耗尽,在随后的实验期间保持着较低且平稳的比生长速率,可见球形棕囊藻能快速吸收氨氮并储存在细胞内,当培养液中氮源耗尽后用于维持细胞的增长。Effect of nitrogen sources on growth of Phaeocystis globosa was studied from the perspectives of nutrient utilization in physio-biochemistry. The results show that under the same initial nitrogen concentration, P. globosa had a higher cell density and chlorophyll a concentration when urea but nitrate or ammonia was used as the sole nitrogen source. Additionally, both nitrate reductase activity and urease activity were regulated by the concentration and uptake rate of ambient nitrogen source, in which the nitrate reductase activity and urease activity maximized when grown with nitrate and urea respectively. Furthermore, a high density of P. globosa ceils may contribute to urease activity rather than nitrate reductase activity, which was observed when urea was used as the sole nitrogen source. Moreover, nitrogen starved P. globosa cells had a very high initial ammonia uptake rate, and the ammonia concentration was depleted to 1.5~tmol/L after cultured for 8h, in which the growth rate of cells stabilized at a low level. The results indicate that the intracellular reserved ammonia source could be used for the cell growth after ambient nitrogen was depleted.

关 键 词：球形棕囊藻 氮源 硝酸盐还原酶 脲酶 

分 类 号：X173[环境科学与工程—环境科学]