Green light as supplementary light for enhancing biomass production of Ettlia sp. and preventing population invasion from other microalgae

Abstract

The biomass and carotenoid productivities of a freshwater microalga, Ettlia sp. YC001 (Chlorophyta, Chlamydomonadales), were investigated in continuous culture systems irradiated with various LEDs. Green light was effectively used by Ettlia sp. for its biomass growth compared to blue and red LED light. This effective use of green light was assumed to be beneficial for Ettlia sp., especially in competition with other microalgae. Thus, in a competition between Ettlia sp. and Chlorella vulgaris, Ettlia sp. out-competed C. vulgaris without losing any overall biomass productivity when green and white LEDs were used simultaneously. However, since Ettlia sp. also showed relatively low oxygen production under green light, further studies are needed on its photosynthesis and biomass production mechanisms. Notwithstanding, LEDs are potentially useful for identifying strain-specific photosynthetic characteristics of microalgae, thereby increasing their biomass productivity and controlling contamination from other microalgae in open culture systems.