营养盐水平对念珠藻胞外有机物产生的影响

Effect of Nutrition Level of Phosphorus and Nitrogen on the Metabolism of the Extracellular Organic Matter of Nostoc flagelliforme

以我国湖泊典型固氮蓝藻发状念珠藻(Nostoc flagelliforme)为研究对象,考察了氮、磷营养盐对发状念珠藻生长特性及其胞外有机物产生的影响.采用藻细胞浓度计数法表征发状念珠藻生长特性;分别采用溶解性有机碳(DOC)、三维荧光光谱(EEM)和紫外-可见光谱法,从总量和主要物质方面分析了发状念珠藻胞外有机物的产生规律.结果表明,在不同氮、磷营养水平下,发状念珠藻的4个关键生长时期基本相同,氮是控制发状念珠藻生长的关键营养控制要素;氮营养元素浓度的增高,有利于发状念珠藻产生胞外有机物,其产生量逐渐增大,而磷营养元素浓度的增高对胞外有机物产生量贡献较小,氮营养盐是发状念珠藻产生胞外有机物的关键限制因子;通过EEM谱图分析,发状念珠藻胞外有机物主要以类氨基酸类物质和类富里酸物质为主.以磷为控制营养盐时,类富里酸是主要的胞外有机物之一,以氮为控制营养盐时,类富里酸产生量极低;作为主要的胞外有机物,蛋白质和碳水化合物的产生规律显著不同,其中蛋白质含量显著高于碳水化合物含量.

In this study,Nostoc flagelliforme,which is a typical nitrogen-fixing cyanobacteria alga in lakes,was selected as the object and effects of nitrogen and phosphate concentration on the growth and the generation of extracellular organic matters（EOM） were investigated.The growth of algae concentration was characterized by counting method.The releasing characteristic of extracellular organic matters（EOMs） was analyzed by DOC,EEM,and spectroscopy methods.At different levels of nitrogen and phosphorus nutrition,Nostoc flagelliforme exhibited a same growth period basically.Nitrogen is the key factor to controlling the growth of Nostoc flagelliforme,compared with phosphate.The increasing of the nitrogen concentration enhanced the concentration of EOMs;the increasing of the phosphate concentration was not good for the releasing of EOMs.Nitrogen is also the key factor to controlling the releasing of EOMs by Nostoc flagelliforme.By the analysis of EEMs,when phosphate was the controlling factor,the main EOMs was amino acid-like and fulvic acid-like organic substances;when nitrogen was the controlling factor,the main EOMs was amino acid-like organic substances.As main components,the concentration of carbohydrate was much lower than that of protein.