氮胁迫对雨生红球藻色素积累与抗氧化系统的影响

选用雨生红球藻CG-06为试验藻株,以BBM为基础培养基,分别设置了0、13.7、27.5、41.2mg·L-1四个硝态氮浓度梯度,分析并探讨在不同硝态氮浓度条件下雨生红球藻生长、生理特性、细胞内主要色素含量的变化以及抗氧化酶活性。结果表明：细胞中色素的积累量和积累速率与初始硝态氮浓度成反比,与抗氧化酶活性呈负相关。缺氮时,培养到第3天的藻细胞中虾青素含量达到4.95μg·mg-1,而对照组在培养到第9天的细胞中才开始产生虾青素,而且在整个培养周期内细胞中的虾青素最大含量仅为4.17μg·mg-1。酶活测定结果显示,虾青素含量较高的红色细胞中,超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GSH-Px）的活性明显高于绿色细胞,且GSH-Px活性最高。研究表明,雨生红球藻可能有两种过氧化防御机制,绿色细胞阶段以抗氧化酶作用为主,在培养后期启动虾青素保护机制,两种机制具有协同作用。

Effects of Nitrate-Nitrogen Stress on Pigment Content and Antioxidant Systems in Haematococcus pluvialis

The effects of different nitrate-nitrogen concentrations on the growth,physiological characteristics,pigment contents and antioxidant enzyme activities were investigated in Haematococcus pluvialis CG-06 grown in BBM media with four series of nitrate-nitrogen concentrations（0,13.7,27.5,41.2 mg·L-1）.The results showed that the accumulation amount and rate of the pigments and the antioxidant enzyme activities in H.pluvialis CG-06 had negative correlation with the initial nitrate-nitrogen concentrations.The astaxanthin accumulation amount in H.pluvialis cells grown in nitrogen-free BBM medium could be up to 4.95μg·mg-1 on the 3rd day,however,the H.pluvialis cells grown in normal BBM medium（control group）started to accumulate astaxanthin only on the 9th day,and its maximum astaxanthin content was 4.17μg·mg-1 during the whole growth period.The determination of antioxidant enzyme activities indicated that superoxide dismutase（SOD）,catalase（CAT） and glutathione peroxidase（GSH-Px） activities in red cells of H.pluvialis with more astaxanthin were always higher than those in green cells,and the maximum antioxidant enzyme activity in H.pluvialis cells was the GSH-Px.In this study,it was suggested that H.pluvialis might have two mechanisms of antioxidative defense.In the vegetative green cell stage,the antioxidase might play a major role and after that the cells started to accumulate astaxanthin for further protection mechanism.Two mechanisms had a synergistic effect.