Energy efficient growth control of microalgae using photobiological methods

Microalgae have garnered interest for the production of valuable molecules ranging from therapeutic proteins to biofuels. However, microalgae also are associated with the considerable problem of phytoplankton bloom. In this study, we demonstrated algal growth using Isochrysis galbana as a model can be controlled photobiologically. Long dark period (24-h light: 24-h dark) unlike common photoperiod resulted in biomass loss and slower growth rates, but were unlikely to cause fatal damage. Algal cell growth can be significantly recovered with the onset of light. Also, it was confirmed that blue light-emitting diode (LED) illumination was able to effectively support cell growth of I. galbana as the sole light source. The blue LED intensity with 200% (580 l×, 18.52 μmol m−2 s−1) based on 8000 l× (98.4 μmol m−2 s−1) fluorescent lamp provided the best support for growth of I. galbana. We verified excessive light intensities lead to inhibition of algal growth, whereas low light intensities also did not promote algal growth. Further, I. galbana cell growth can be controlled using blue LED with extremely high LED intensities. These results may provide means to control algal population for either goal of growth or inhibition through proper use of such illumination.