二丁基羟基甲苯对雨生红球藻虾青素和油脂积累的影响

Effects of Butylated Hydroxytoluene on Accumulation of Astaxanthin and Lipids in Haematococcus pluvialis LUGU

以雨生红球藻(Haematococcus pluvialis)为对象,研究高光照、缺氮条件下,外源添加不同浓度的二丁基羟基甲苯(Butylated hydroxytoluene, BHT)对雨生红球藻生长、虾青素积累、油脂合成、脂肪酸组成、碳水化合物、蛋白含量以及虾青素和脂肪酸合成相关酶基因的影响。结果显示,添加不同浓度的BHT后,2mg/LBHT添加组虾青素积累量为最高,显著高于其他实验组和对照组(P<0.05),达到31.66 mg/g,是对照组的1.87倍。油脂含量达45.56%,高于同期对照组(39.06%),脂肪酸组成变化不显著。在此条件下,虾青素合成关键酶基因dxs和bkt表达水平分别是对照组的5.19倍和2.04倍;脂肪酸合成关键酶基因kas和acp表达水平较对照组显著提高(P<0.05),分别是对照组的4.56倍和3.02倍。与对照组相比,2 mg/L BHT添加组的碳水化合物和蛋白含量均呈下降趋势。研究表明,在胁迫条件下,外源添加适量浓度的BHT能有效促进雨生红球藻中虾青素的积累,同时提高了藻细胞内的油脂含量。

Haematococcus pluvialis is a microalga, and this species is economically important since it is a rich source of natural astaxanthin, which is considered a "super anti-oxidant." The study was conducted using H. pluvialis LUGU filtrated from Lugu Lake in Yunnan Province, China. Studies have shown that under stress, the exogenous addition of appropriate concentration of butylated hydroxytoluene(BHT) can effectively promote the accumulation of astaxanthin and increase the content of lipids in the algal cells. The effects of BHT on several traits were investigated under stress conditions(high illumination and nitrogen deficiency), including the impact on growth of algae;the accumulation of astaxanthin;the synthesis of lipids;the composition of fatty acids, carbohydrates and protein;the expression level of the key enzyme gene of astaxanthin;and fatty acid biosynthesis. In this study, the different concentrations of BHT(0, 1, 2, and 3 mg/L) were achieved through single factor experiments in algal cell culture medium. Results from these experiments showed that BHT treatment does not effectively promote the algae growth, but it does affect the accumulation of astaxanthin in algae cells. There was a significant dose effect depending on the BHT treatment applied to H. pluvialis. After examining BHT additions of different concentrations, astaxanthin accumulation was determined to be the highest after the 2 mg/L BHT treatment, and it was significantly higher than that resulting from other treatments or the control group(P<0.05). Moreover, astaxanthin accumulation was 1.87 times higher than that in the control group, reaching 31.66 mg/g. The lipid content of the 2 mg/L BHT treatment was 45.56%, which was also higher than that in the control(39.06%). Under these conditions, the expression levels of the key enzyme genes of astaxanthin synthesis, dxs and bkt, were 5.19 folds and 2.04 folds, respectively, as those of the control, and the expression levels of the key enzyme genes of fatty acid synthesis, kas and acp, were significantly higher than those of the control(P<0.05), being 4.56 folds and 3.02 folds, respectively, as those of the control. Contrastingly, the carbohydrate and protein contents decreased compared to those of the control group. Overall, our results also show that BHT can increase accumulation of astaxanthin and increase the content of lipids in the algal cells when administered at an appropriate dose.