不同培養條件對擬球藻生長與油脂生合成量之影響

The Effect of Cultivation Conditions on the Growth and Oil Production of 'Nannochloropsis sp'

本研究以光生化反應器批次方式培養擬球藻（Nannochloropsis sp.），探討培養基組成對擬球藻生長與油脂生合成量的影響。包括不同碳源濃度（NaHCO3,0.1、0.2、0.3M）、不同氮源濃度（NaNO3,0.1、0.2、0.3g/L）與酸鹼值（pH,8.4、9、9.5、10）等，培養溫度與鹽度分別為30℃與25g/L。實驗結果以NaHCO3濃度0.1M、NaNO3濃度0.3g/L、pH8.4之培養基組成有最高的比生長速率，1.28day-1。當碳源與氮源二者濃度增加至NaHCO3 0.3M和NaNO3 0.3g/L之培養，擬球藻之遲滯期（lag phase）延長且抑制擬球藻生長。培養液pH值隨氮源濃度增加而有增加趨勢。在不同碳源濃度下培養，培養液pH值隨碳源濃度增加而下降。於碳源充足而限制氮源濃度（NO3-濃度小於0.15g/L）條件下培養，油脂占藻體乾重比例達23.％。於限制氮源濃度條件下培養，有利於擬球藻生合成油脂。

The effect of the chemical composition of a medium on the biomass and oil production of Nannochloropsis sp. was investigated using batch cultivation of photobioreactors. The culture media were 0.1, 0.2, and 0.3 M sodium bicarbonate, and 0.1, 0.2, and 0.3 g/L nitrate, at pH values of 8.4, 9, 9.5, and 10, a temperature of 30 °C, and a salinity of 25 g/L. The optimal proportional growth rate was 1.28 d-1, with carbon concentration, nitrogen concentration, and pH being 0.1 M, 0.3 g/L, and 8.4, respectively. When the concentration of carbon and nitrogen was increased to 0.3 M NaHCO3 and 0.3g/L NaNO3, the lag phase was extended and inhibited the growth of algae. The pH of the culture medium increased as the nitrogen concentration was increased. However, the pH of the culture medium decreased as the carbon concentration was increased. During the cultivation, a sufficient carbon supply and nitrogen limitation（less than 0.15 g/L of NO3-）, resulted in oil production of 23%. The nitrogen limitation during the cultivation of Nannochloropsis sp. can enhance the biosynthesis of oil.