不同氮源对布朗葡萄藻生长、总脂和总烃含量的影响

Effects of nitrogen sources on the growth,contents of total lipids and total hydrocarbons of Botryococcus braunii

以能源微藻布朗葡萄藻Botryococcus braunii764和Botryococcus braunii765为实验材料,采用实验室一次性培养的方法,研究了不同氮源及浓度对其生长、总脂和总烃含量的影响。结果表明,B.braunii764和B.braunii765的最适氮源均为硝态氮,且均能够利用硝态氮、亚硝态氮、铵态氮和尿素进行生长,但是不同氮源及其浓度对这两株藻的生长、总脂和总烃含量的影响不同。B.braunii764生长速度较B.braunii765缓慢,但是B.braunii764的总脂和总烃含量均高于B.braunii765,最高分别达27.61%和34.21%。以硝态氮为氮源时,B.braunii764的细胞OD值、生物量、总脂和总烃含量分别为1.38、1.81g/L、27.61%和34.21%,均显著高于其它试验组,而以尿素为氮源时,B.braunii765的最大OD值为1.87,以硝态氮为氮源时,其生物量(2.15g/L)和总烃含量(27.89%)最高,而铵态氮对二者生长的促进作用以及总脂和总烃含量的影响不明显。综合考虑,硝态氮是两株葡萄藻较为理想的氮源,而B.braunii764可以作为一种较有潜力的能源微藻进行开发利用。

Two microalgae strains, Botryococcus braunii 764 and Botryococcu braunii 765, were chosen for studying the effects of different nitrogen sources and concentrations on the growth, total lipids and total hydrocarbons of energy microalgae in laboratory. These culture were grown in Chu10 media at ca.24 ℃, light intensity of ca.100 μmol photons·m^-2·s^-1, and light-dark cycle of 12∶12. Four nitrogen sources, ie. nitrate, nitrite, ammonium and urea, and six concentrations of 0.5, 1, 2, 4, 8 and 10 mmol N/L for each source were applied. The results showed that all four nitrogen sources could be utilized by both B. braunii 764 and B. braunii 765 for their growth, which, however, varied significantly with nitrogen sources, nitrogen concentrations and microalgae strains. Nitrate was the optimal nitrogen source for the growth of both microalgae strains. The optical density, biomass, total lipids and total hydrocarbons of B. braunii 764 with nitrate were 138, 1.81 g/L, 27.61% and 34.21% （of its cell dry weight）, respectively, which were significantly higher than that of other three nitrogen sources, while for B. braunii 765 the biomass and total hydrocarbons with nitrate were also higher than that of other nitrogen treatments, being 2.15 g/L and 27.89%, respectively, with the exception of the optical density that was the highest with urea （1.87）. In comparison with B. braunii 765, the growth rate of B. braunii 764 was a little slow, but its total lipids and total hydrocarbon were higher than that of B. braunii 765, being 27.61% and 3421%, respectively, compared with 15.75% and 27.89% for B. braunii 765. Significant hormesitic effects with nitrogen concentrations were also observed for both microalgae strains. At the concentration of 2.0 mmol N/L nitrate both the total lipids and total hydrocarbon of B. braunii 764 were the highest, 27.61% and 34.21%, respectively, while B. braunii 765 reached its highest total lipids of 15.75% at the concentration of 4.0 mmol N/L nitrite, and total hydrocarbons of 27.89% at the concentration of 8.0 mmol N/L nitrate. Our findings indicated that overall B. braunii 764 could be considered as an energy alga candidate for the further exploitation and utilization of its potential.