亚硒酸钠对微拟球藻生长、抗氧化酶活性及硒含量的影响

The Impact of Sodium Selenite on the Growth, Antioxidant Enzyme Activity and Selenium Content of Nannochloropsis oceanica

摘要: 为探究不同质量浓度的亚硒酸钠对微拟球藻(Nannochloropsis oceanica)生长、抗氧化酶活性及硒含量的影响，试验设计0 (对照)、3、6、12、24 mg/L共5个处理组，分别为A、B、C、D和E组，每组设3个平行，定期检测各组微拟球藻的藻细胞密度、相对生长速率、抗氧化酶活性(过氧化氢酶CAT、谷胱甘肽过氧化物酶GSH-Px和超氧化物歧化酶SOD)及硒含量的变化，藻初始接种密度为5 × 10⁶ cells/mL。试验结果表明：C组从第3天开始藻细胞密度显著高于其他组(P < 0.05)，且这一优势持续至培养结束，E组结果与C组刚好相反；C组的相对生长速率显著高于对照组、D和E组(P < 0.05)，与B组无显著性差异(P > 0.05)；从培养第3天至结束，C组微拟球藻细胞密度显著高于对照组和其他浓度组(P < 0.05)，而E组微拟球藻细胞密度显著低于对照组和其他浓度组(P < 0.05)；C组微拟球藻的相对生长速率显著高于对照组、D和E组(P < 0.05)；添加亚硒酸钠能够显著提高微拟球藻抗氧化酶活性(P < 0.05)，在培养至第5天时，C组微拟球藻的CAT和GSH-Px酶活性最高，而E组微拟球藻的SOD酶活性最高，在培养至第10天时，各组的抗氧化酶活性均较第5天时有所降低；微拟球藻细胞内硒含量随着添加亚硒酸钠质量浓度增加而增加，但浓度过高微拟球藻的富集能力也会有所下降。研究表明，添加低浓度的亚硒酸钠能够促进微拟球藻的生长和抗氧化酶活性并有效富集硒，本试验条件下，微拟球藻培养的适宜亚硒酸钠添加浓度为6 mg/L。

Abstract: To investigate the effects of different concentrations of sodium selenite on the growth, antioxidant enzyme activities, and selenium content of Nannochloropsis oceanica, the experiment was designed with five treatment groups: 0 (A, control), 3 (B), 6 (C), 12 (D), and 24 mg/L (E), each with three replicates. The cell density, relative growth rate, antioxidant enzyme activities (catalase, CAT; glutathione peroxidase, GSH-Px; and (superoxide dismutase, SOD), and selenium content of N. oceanica were measured periodically. The results showed that when the initial inoculation cell density of N. oceanica was 5 × 10⁶ cells/mL, from the third day of cultivation until the end, the cell density in the group C was significantly higher than that in the other groups (P < 0.05), while the cell density in the group E was significantly lower than that in the other groups (P < 0.05). The relative growth rate of N. oceanica in the group C was significantly higher than that in the groups A, D, and E (P < 0.05). The addition of sodium selenite significantly increased the antioxidant enzyme activities of N. oceanica (P < 0.05). On the fifth day of cultivation, the CAT and GSH-Px activities in the group C were the highest, while the SOD activity in the group E was the highest. By the tenth day of cultivation, the antioxidant enzyme activities in all groups had decreased compared to the fifth day. The intracellular selenium content of N. oceanica increased with the increasing concentration of sodium selenite, but the selenium accumulation capacity decreased when the concentration was too high. The study indicates that adding a low concentration of sodium selenite can promote the growth and antioxidant enzyme activities of N. oceanica and effectively enhance selenium accumulation. Under the experimental conditions, the optimal concentration of sodium selenite for N. oceanica cultivation was found to be 6 mg/L.