缺氮胁迫下生长素对普通小球藻生长及油脂积累的影响

Effects of auxin on growth and lipid accumulation of Chlorella vulgaris under nitrogen stress

以普通小球藻为研究对象,在氮缺乏条件下分别添加天然生长素吲哚乙酸(IAA)、人工合成生长素萘乙酸(NAA)及2,4-二氯苯氧乙酸(2,4-D),研究了不同生长素添加量下普通小球藻的生长特征、油脂积累及藻油脂肪酸组成。结果表明:最佳的生长素添加量分别为IAA 1.0 mg/L、NAA 2.5 mg/L、2,4-D 1.0 mg/L;在IAA、NAA、2,4-D最佳添加量下,普通小球藻最高生物量分别为158、159、164 mg/L,是单一缺氮(ND)培养下生物量的1.27、1.28、1.32倍,与整个培养周期前8 d正常培养(BG11)下的微藻生物量相比无显著性差异,生长素有效抵消了缺氮胁迫对生物量的负面影响;在IAA、NAA、2,4-D最佳添加量下,普通小球藻最大总脂含量分别是BG11培养条件下的1.72、1.64、1.74倍,最大总脂产量分别为61.38、58.83、64.22 mg/L,是BG11组的1.49、1.43、1.56倍,而ND组最大总脂产量低于BG11组;在最佳生长素添加量下,普通小球藻细胞内最大甘油三酯含量分别为27.97%、25.66%、33.21%,最大甘油三酯产量分别为44.19、40.80、54.46 mg/L,均明显高于BG11组;C16~C20脂肪酸成分分别占总脂肪酸的71.99%、73.75%、84.81%。研究表明,缺氮胁迫下3种生长素对普通小球藻生长及油脂合成具有明显促进作用,其中2,4-D效果最佳。

Natural auxin indole acetic acid(IAA), synthetic auxin naphthalene acetic acid(NAA) and 2,4-dichlorophenoxy acetic acid(2,4-D) were added into a nitrogen deficient culture medium to study the effects of different auxin dosage on growth characteristics, lipid accumulation and algal oil fatty acid composition of Chlorella vulgaris. The results showed that the optimal dosages of auxins were IAA 1.0 mg/L, NAA 2.5 mg/L and 2,4-D 1.0 mg/L. Under the optimal dosage of auxins, the highest biomasses of Chlorella vulgaris were 158, 159 mg/L and 164 mg/L respectively, which were 1.27, 1.28 times and 1.32 times of the deficiency nitrogen(ND)cultivation, and there was no significant difference in the biomass under normal culture(BG11) for 8 d in the whole cultural period. Auxin effectively offsetted the negative effect of nitrogen stress on biomass. The maximum total lipid content of Chlorella vulgaris with 1.0 mg/L IAA, 2.5 mg/L NAA and 1.0 mg/L 2,4-D groups were 1.72, 1.64 times and 1.74 times of that in BG11 group, respectively. The maximum total lipid yields were 61.38, 58.83, 64.22 mg/L, respectively, which were 1.49, 1.43,1.56 times of those in BG11 group. The maximum triglyceride contents were 27.97%, 25.66% and 33.21%, and the maximum triglyceride yields were 44.19, 40.80, 54.46 mg/L, respectively, which were significantly higher than those in BG11 group. The proportion of C16-C20 fatty acids in total fatty acids were 71.99%, 73.75% and 84.81% respectively. The research showed that the three auxins had a significant positive effect in algal growth and lipid synthesis of Chlorella vulgaris, and the 2,4-D was the best.