MORPHOLOGY, GROWTH AND PHOTOSYNTHETIC RESPONSES OF THE CYANOBACTERIUM ARTHROSPIRA PLATENSIS TO DIFFERENT WAVEBANDS IN SOLAR SPECTRUM

Light is known to regulate morphological development and photosynthetic performance of the economically important cyanobacterium, Arthrospira platensis. However, light quality under different wavelengths on its growth and physiology is yet to be understood. In this study, we grew A. platensis D-0083 trichomes in quartz tubes covered with different cutoff foils and one band-pass filter, so that the cells received different wavebands of irradiances, and measured its growth, morphology and photosynthetic performances. Spirals of A. platensis D-0083 were compressed and the biomass increased with exposures under all wavebands. Both the wavebands of UV-A + blue light (320500 nm) and red light (600700 nm) could initiate the spiral compression, growth and photosynthetic activities in A. platensis D-0083 efficiently. The efficiencies per unit energy of irradiance to induce helix pitch changes in wavebands 320500, 395700, 510700 and 610700 nm were 0.070, 0.015, 0.021 and 0.045 m/(Wm2) respectively. Waveband 320500 nm had little suppression on effective quantum yield (Fv'/Fm'), electron transfer rate (ETR) and phycocyanin (PC) fluorescence emission of the filaments but led to spiral compression and growth efficiently. The waveband-dependent responses in spiral compression and specific growth rate appeared to be consistent with the photosynthetic capability under the different light regimes.