亚硒酸钠对蛋白核小球藻生长及抗氧化酶活性的影响

Effects of sodium selenite on growth and antioxidant enzyme activity of green alga Chlorella pyrenoidosa

为探究不同质量浓度亚硒酸钠对蛋白核小球藻Chlorella pyrenoidosa生长及抗氧化酶活性的影响,试验设计0、2、4、6、8、10、20、40、60、80、100 mg/L共11个亚硒酸钠处理组,定期监测不同处理组小球藻细胞密度、吸光度值及抗氧化酶活性的变化。结果表明:小球藻初始细胞密度为1×106 cells/mL时,添加2、4 mg/L的亚硒酸钠对蛋白核小球藻细胞生长具有显著促进作用(P<0.05),而6~100 mg/L亚硒酸钠对小球藻细胞生长具有显著抑制作用(P<0.05);试验第7天时,6~10 mg/L亚硒酸钠处理组藻细胞恢复生长,至第13天时藻细胞生长速率与对照组无显著性差异(P>0.05),而20~100 mg/L亚硒酸钠处理组小球藻生长速率显著低于对照组(P<0.05),且试验前7 d为负值,第9天开始恢复为正值;蛋白核小球藻含硒量随亚硒酸钠质量浓度的增加而增加;低质量浓度(2~4 mg/L)的亚硒酸钠能诱导小球藻细胞超氧化物歧化酶(SOD)活性显著增加(P<0.05),而高质量浓度(20~100 mg/L)的亚硒酸钠则能够诱导藻细胞谷胱甘肽过氧化物酶(GSH-Px)活性显著增加(P<0.05);用40~100 mg/L亚硒酸钠处理蛋白核小球藻时,藻细胞出现三分裂、四分裂及细胞团的现象。研究表明,低质量浓度硒能促进蛋白核小球藻的生长,而高质量浓度硒具有抑制作用,不同抗氧化酶对硒的敏感性不同,小球藻富硒培养时亚硒酸钠的适宜添加质量浓度为2~4 mg/L,且培养时间应控制在一个月内,以免藻体中毒死亡。

Green alga Chlorella pyrenoidosa in exponential growth phase was inoculated into a 250 mL Erlenmeyer flask containing 100 mL culture medium at initial density of 1×106 cells/mL and cultivated at sodium selenite concentrations of 0,2,4,6,8,10,20,40,60,80,and 100 mg/L under conditions of 25℃,light intensity of 25μmol/(m2·s),and photoperiod of 12 h L∶12 h D.The cell density,optical density(OD)and antioxidant enzyme activities of the green alga were monitored regularly to investigate the effect of different concentrations of sodium selenite on the growth and antioxidant enzyme activity of the green alga.The results showed that the growth was promoted significantly in the green alga at initial cell concentration of 1×106 cells/mL exposed to 2 mg/L and 4 mg/L of selenite(P<0.05),and was inhibited significantly in the green alga exposed to 6-100 mg/L selenite significantly(P<0.05).On the 7th day of the experiment,the growth rates were found to be recovered in the green alga in 6-10 mg/L selenite treatment groups,without significantly different from the control group(P>0.05).However,the green alga in 20-100 mg/L selenite treatment groups had significantly lower growth rates than that in the control group did(P<0.05),degrowth in the early stage of the experiment,and recovered to positive growth value from the 9th day.There was increase in the selenium content of the green alga with increasing sodium selenite concentration within the this study.There was increase in the superoxide dismutase(SOD)activity of the green alga in low selenite at concentration(2-4 mg/L)groups significantly,and there was increase in glutathione peroxidase(GSH-PX)activity in high selenite concentration(20-100 mg/L)groups significantly.The fact that one cell was divided into three or four cells was observed the green alga in the 40-100 mg/L sodium selenite groups,with cell aggregation.The findings indicated that low concentration selenium led to promote growth of the green alga,and that high concentration selenium resulted in inhibition of the growth of the green alga,with the suitable sodium selenite concentration of 2-4 mg/L within one month culture,so as to avoid the death of alga poisoning.