EFFECT OF LIGHT-EMITTING DIODE LIGHT QUALITY ON THE GROWTH AND PHYSIOLOGICAL AND BIOCHEMICAL CHARACTERISTICS OF NOSTOC SPHAEROIDES

The influence of different Light-Emitting Diode (LED) wavelengths (red 637 nm, green 529 nm, blue 453 nm and white light, set cool white fluorescence as control) on the growth and the physiological and biochemical characteristics of Nostoc sphaeroides Ktzing were studied. Results showed that in the initial growth stage, red light promoted the synthesis of phycocyanin and inhibited the phycoerythrin, and the former was also increased by blue and green lights. In the late growth stage, the contents of chlorophyll a and carotenoids in the colonies which cultured under red light accounted for 1.33% and 0.24% of the dry weight, while they were about 1.0% and 0.16% respectively in green, white, or cool white fluorescence cultures, and 0.45% and 0.11% respectively in blue light culture. The content of total amino acids in red light culture was 23.1% in dry weight, which was 1.58 times of the control group. There was no significant difference between the contents of reducing sugars in the cultures under different light wavelengths except blue light. The mean specific growth rates of the white light culture and the cool white fluorescence cultures were about 1.3 and 1.5 times of those in other monochromatic light cultures, respectively.