The Inhibition Efficiency of Blue Light And Light Intensity On The Growth Rate of Microcystis Aeruginosa

Lake eutrophication is associated with the occurrence of cyanobacterial blooms which have a negative effect on other organisms. Several studies demonstrated that blue LED irradiation inhibits the growth rate of cyanobacteria Microcystis aeruginosa, while the efficiency varies from study to study. In this paper, the focus was on the effects of light intensity on the growth of M. aeruginosa because the light intensity used in the precious studies varied from 12 to 45 μmol photons m^-2 s^-1. Growth experiment of M. aeruginosa was conducted with 32 μmol photons m^-2 s^-1 blue light and fluorescent light, and the results were compared with the findings of previous reports. Furthermore, co-culture of M. aeruginosa and diatom Nitzschia palea was also prepared. The growth rate of M. aeruginosa was 0.33 day^-1 and 0.11 day^-1 under fluorescent light and blue light, respectively. The blue light dropped the growth rate by 67%. Compared with previous studies, the inhibition efficiency seemed to be the best at 20 μmol photons m^-2 s^-1. The growth rate of N. palea was 0.62 day^-1 and 0.36 day^-1 under fluorescent light and blue light, respectively. Since the efficiency of N. palea by blue light (42%) was smaller than that of M. aeruginosa, blue light is considered to be a countermeasure to cyanobacterial blooms.