利用平板反应器大量培养高产油绿藻——尖状栅藻的生长和油脂积累规律

以新近分离的淡水绿藻--尖状栅藻(Scenedesmus acuminatus)为研究对象,将改良的BG-11培养基中的初始NaNO₃浓度降低为6.0mmol/L和3.6mmol/L,利用新设计的内置拉筋平板式光生物反应器对尖状栅藻(S. acuminatus)进行大量培养。测定不同时相的生物量、总脂含量、脂组分含量及脂肪酸组成和含量,分析尖状栅藻(S. acuminatus)大量培养时的生长和油脂积累规律。当初始NaNO₃浓度为6mmol/L时其最高生物量(6.27g/L)明显高于初始NaNO₃浓度为3.6mmol/L时的生物量(5.30g/L);而最高的总脂含量在初始NaNO₃浓度为3.6mmol/L时获得为干重的56.6%,高于初始NaNO₃浓度为6mmol/L时的总脂含量(51.6%)。总脂经硅胶柱层析分级后得到三种类型的脂组分:中性脂、糖脂和磷脂,随着培养时间的延长中性脂含量逐渐增加,培养至18d后,中性脂的含量分别达到总脂的 90.9%(6 mmol/L NaNO₃)和 92.0%(3.6 mmol/L NaNO₃)及干重的 47.5%(6.0 mmol/L NaNO₃)和 51.4%(3.6 mmol/L NaNO₃)。主要脂肪酸组成为棕榈酸、棕榈油酸、硬脂酸、油酸、亚麻油酸和亚麻酸,这六种脂肪酸在不同时相的含量变化范围分别为89.92%~96.18%(占总脂肪酸)和12.5%~50.7%(占细胞干重)。总脂、中性脂及总脂肪酸单位体积产率分别为:0.18 g/L/d,0.16 g/L/d和0.15 g/L/d(6.0 mmol/L NaNO₃)及0.16 g/L/d,0.15 g/L/d和0.15 g/L/d(3.6 mmol/L NaNO₃)。研究结果表明,尖状栅藻(S. acuminatus)是一株易于规模化培养、脂肪酸组成适合于生物柴油生产的高产油微藻。

The Growth and Lipids Accumulation Pattern of Oleaginous Green Microalga Scenedesmus acuminatus Large Volume Cultured in Flat Panel Photobioreactor

Scenedesmus acuminatus was a new isolated freshwater green microalga cultured in modified BG-11 medium. In order to improve the rapid accumulation of the lipids, the initial NaNO₃ concentration reduced to one third and one fifth of the original NaNO₃ concentration in the BG-11 medium, 6.0mmol/L and 3.6mmol/L, respectively. It was large volume cultured in a new-designed internally installed tiepiece flat panel photobioreactor. To analyze the growth and oil accumulation pattern of S.acuminatus mass cultures, the biomass, total lipids content, lipid compositions, and fatty acids profiles in different phase were investigate. When the initial NaNO₃ concentration was 6.0mmol/L, the biomass(6.27g/L)was higher than the biomass(5.30g/L) of 3.6mmol/L treatment. While, the highest lipids content of 56.6% of dry weight was occurred at 3.6mmol/L treatment. The total lipids content was fractionated by solid phase extraction (SPE) into three broad classes: neutral lipid (NL), glycolipid (GL) and phospholipid (PL). The content of neutral lipid increased along with the culture time, and it reached to 90.9% and 92.0% of the total lipids, 47.5% and 51.4% of dry weight when the initial NaNO₃ concentration was 6.0mmol/L and 3.6 mmol/L, respectively. The major fatty acids of S.acuminatus were C16:0, C16:1, C18:0, C18:1, C18:2,and C18:3,which together accounted for 89.9%~96.2% of the total fatty acids content and 12.5%~50.7% of dry weight. The volumetric productivity of total lipids, neutral lipids and total fatty acids of S.acuminatus were 0.18g/L·d, 0.16 g/L·d and 0.15 g/L·d when the initial NaNO₃ concentration was 6.0mmol/L and 0.16g/L·d, 0.15g/L·d and 0.15g/L·d when the initial NaNO₃ concentration was 3.6 mmol/L, respectively. The results showed that S.acuminatus was a hyper-oil producing strain that is easy to large-scale cultivation and its profiles of fatty acids is suitable for biodiesel production.