以BG11为基本培养液,研究了不同质量浓度NaNO₃(37.5~1 875.0 mg.L^-1)对微藻P9 (Klebsormidium sp.)、TH6(Oedocladium sp.)和CF5(Stigonema sp.)生长及总脂肪酸含量和组成的影响。结果显示,调整(减少或增加)培养液中NaNO₃的质量浓度,对3种微藻的生长量及总脂肪酸含量和脂肪酸组成均有一定的影响;NaNO₃的质量浓度较低(37.5或75.0 mg.L^-1),3种微藻的鲜质量随培养时间的延长呈先逐渐增加然后略有降低的趋势;而在NaNO₃质量浓度为150.0~1 875.0 mg.L^-1的条件下,在一定的培养时间(18~33 d)内,3种微藻的鲜质量均逐渐增加;总体上看,3种微藻的生长量随NaNO₃质量浓度的提高呈现逐渐增加的趋势,但仅在含1 875.0 mg.L-1NaNO₃的培养液中3种微藻的生长量高于对照(1 500.0 mg.L^-1NaNO₃)。在含375.0 mg.L^-1NaNO₃的培养液中培养33 d,微藻P9的总脂肪酸含量最高(25.39%),是对照的1.79倍,软脂酸、亚油酸、油酸和硬脂酸的相对含量分别是对照的2.50、2.72、2.24和2.08倍;在含37.5 mg.L^-1NaNO₃的培养液中培养33 d,微藻TH6的总脂肪酸含量最高(20.69%),是对照的1.89倍,软脂酸、亚油酸和油酸的相对含量分别是对照的3.37、1.79和1.92倍;不同处理组间微藻CF5的总脂肪酸含量及组成有一定差异,但随着NaNO₃质量浓度的提高变化趋势不明显。研究结果表明,适当提高培养液中的NaNO₃浓度对微藻的生长有一定的促进作用,不同种类微藻适宜的NaNO₃浓度有一定的差异。综合考虑生长量和总脂肪酸含量及脂肪酸组成等因素,确定适宜于微藻P9、TH6和CF5培养的NaNO₃质量浓度分别为375.0、37.5和150.0 mg.L^-1。

Effect of different concentrations of NANO₃(37. 875.0 mg. L^-1)on growth and content and composition of total fatty acids of three microalgae including P9(Klebsormidium sp), TH6(Oedocladium sp ) and CF5 (Stigonema sp )was studied using BG11 as basic liquid medium. The results show that NANO₃ concentration adjustment (increase or decrease) in liquid medium has a certain influence on increment, total fatty acid content and fatty acid composition of three microalgae. In condition of lower concentration of NANO₃ (37. 5 or 75.0 mg.L^-1 ) the fresh weight of three microalgae appears the change trend of first gradually increasing and then slightly decreasing with culture time prolonging. But in condition of 150 0-1 875.0 mg. L^-1NANO₃, the fresh weight of three microalgae increases gradually during a certain culture time(18-33 d). In general, three microalgae increments appear gradually increasing trend with NANO₃ concentration rising, but three microalgae increments appear gradually increasing trend with NaNO3  concentration rising, but three microalgae increments only in the liquid medium with I 575. 0 mg. L^-1 NANO₃are higher than that of the control (1 500.0mgNANO₃ ) On culture for 33 d in he liquid medium with 375.0 mg INANO₃, total fatty acid content of microalga P9 is the highest with a content of 25. 39%, which is 1. 79 times compared the control, and the relative contents of palmitic acid, linoleic acid, oleic acid and stearic acid are 2. 50 times, 2. 72imes. 2. 24 times and 2.08 times compared the control, respectively. The total fatty acid content omicroalga TH is the highest with a content of 20.69% under the condition of 37.5 mg. L^-1 NANO₃ for33 d, which is 1. 89 times compared the control and the relative contents of palmitic acid. linoleic acid and oleic acid are 3. 37 times, 1.79 times and 1.92 times compared the control, respectively. However the total fatty acid content and fatty acid composition of microalga CF5 have a certain difference among different treatment groups, but there is no obvious change trend with NANO₃ concentration rising. It is suggested that growth of microalgae can have a certain promotionby properly increasing NANO₃ concentration in liquid medium, but the suitable NANO₃ concentration for different species of microalgaeis various. By comprehensive consideration of some factors, such as increment, total fatty acid content and fatty acid composition, the appropriate liquid medium to microalga P9, TH6 and CF5 is BG1I liquid medium containing 375.0, 37.5 and 150.0 mg. L^-1 NANO₃, respectively.