植物激素与底物浓度对小球藻生长及油脂积累的影响

Effects of phytohormones and substrate concentration on Chlorella vulgaris growth and lipid accumulation

利用植物激素提高微藻生长速率及油脂合成速率是降低微藻生物柴油开发成本的有效手段之一.对比不同浓度天然植物激素吲哚-3-乙酸(IAA)和人工合成类激素1-萘乙酸(NAA)作为微藻培养添加剂对小球藻(Chlorella vulgaris)生长及脂质积累的影响,以BG11培养基作为培养底物,探讨不同底物浓度(10%、25%、50%、75%、100%)对植物激素施用效果的影响.结果显示,两种植物激素对小球藻生长及脂质合成影响显著(P<0.05),IAA的促生长效果优于NAA,最佳施用浓度均为2 mg/L,培养15 d后所获生物量为(525.87±5.91)mg/L、(367.72±4.1)mg/L,分别是对照组生物量的2.48倍和1.7倍;IAA和NAA浓度与脂质积累呈线性相关,IAA在0.05-2 mg/L时表现为促进中性脂积累,NAA在1-5 mg/L时表现为促油脂积累;2 mg/L IAA和2 mg/L NAA诱导后的小球藻生物质产率及油脂产率最高,分别为(35.06±0.39)、(24.52±0.27)mg L^-1 d^-1,(21.96±0.62)、(14.38±0.09)mg L^-1 d^-1,与未加植物激素对照组相比,分别提高了59.68%、41.23%、74.99%、61.78%;小球藻在不同底物浓度中生长及脂质积累差异显著(P<0.05),但对植物激素施用效果影响不明显.本研究表明植物激素对微藻培养体系影响巨大,低浓度IAA与NAA的施用均有助于提升培养效率,且满足生态效益的要求,但从经济效益角度考虑,2 mg/L NAA更适宜作为小球藻养殖的植物激素及添加剂量.

The use of phytohormones to increase the growth rate of microalgae and the rate of oil synthesis is an effective approach to decrease the cost of microalgae biodiesel development. A comparative study was conducted on the effects of different concentrations of natural phytohormone indole-3-acetic acid(IAA) and synthetic hormone 1-Naphthaleneacetic acid(NAA) as microalgae culture additives on the growth and lipid accumulation of Chlorella vulgaris. In this study, the effects of different substrate concentrations(10%, 25%, 50%, 75%, and 100%) on the application of phytohormone were studied and compared using the BG11 medium as the culture substrate. The results showed that the two plant hormones had a significant effect on the growth and lipid synthesis of C. vulgaris(P < 0.05). The dose of 2 mg/L IAA had a better growth promoting effect than 2 mg/L NAA. After a 15-day culture period, the biomass obtained was 525.87 ± 5.91 mg/L and 367.72 ± 4.1 mg/L, respectively, which were 2.48 and 1.7 times higher than that of the control groups. The concentrations of IAA and NAA were linearly correlated with the lipid accumulation. IAA showed a neutral lipid accumulation at 0.05-2 mg/L, while NAA showed the lipid accumulation at 1-5 mg/L. The biomass and oil yield of C. vulgaris were the highest after the induction of 2 mg/L IAA and 2 mg/L NAA with the value of 35.06 ± 0.39 and 24.52 ± 0.27 mg L^-1 d^-1, and 21.96 ± 0.62 and 14.38 ± 0.09 mg L^-1 d^-1, respectively. Compared to the control group, these values increased by 59.68%, 41.23%, 74.99%, and 61.78%, respectively. The accumulation of C. vulgaris growth and lipid increased significantly in different substrate concentrations. The difference was significant(p < 0.05);however, the effect on the application of phytohormone was not significant. This study shows that phytohormones greatly influence the microalgae culture system. The application of low concentration IAA and NAA can help in improving the efficiency of the culture system and meet the requirements of eco-efficiency. However, from the perspective of economic efficiency, 2 mg/L NAA is more suitable as a phytohormone additive for C. vulgari culture than 2 mg/L IAA.