Effects of flashing light-emitting diode (LED) of several colors on the growth of the microalga Isochrysis galbana

The growth rate of Isochrysis galbana was determined under flashing light conditions (104 μmol m-2s-1 light intensity, 10 kHz frequency, and 50% of the duty cycle) of several colors. The most suitable light for the growth of I. galbana was blue (dominant wavelength: 470 nm). After six days, the cell density under blue light was 34.0 × 105 cells mL-1, and was 1.4, 1.6, 1.8,and 2.2 times higher than those under white, red, white non-flashing, and green light, respectively. The peak wavelengths of white and blue lights are nearly consistent with the absorbance maxima of major pigments, which are chlorophylls and xanthophylls, in I. galbana. White and blue light were considered to be most effective for I. galbana growth.