Fig. 4 shows the growth of D. tertiolecta with fluorescent light under these three levels of light intensity (100, 200, and 350 lE/ (m2 s)) under a photoperiod of 15 h light: 9 h dark, 4% CO2, temperature of 23 C, and pH of between 6.4 and 7.0 in culture flask. A significantly different cell growth rate was observed with a light intensity between 100 and 200 lE/(m2 s), while a slightly different cell growth rate was found with a light intensity between 200 and 350 lE/(m2 s). The fastest cell growth rate was obtained with the highest light level and the cell densities reached 1.2 107 cells/ mL on the eighth day.