Effect of continuous exposure to low-dose-rate gamma irradiation on cell growth and lipid accumulation of marine microalgae

Microalgae are a promising alternative source of lipid for biodiesel production. One of the most important decisions is biomass productivity and the lipid content of microalgae. However, few studies have investigated the correlation between low-dose-rate (LDR) chronic irradiation and lipid production using microalgae to date. The present study was undertaken to investigate whether the LDR chronic irradiation increases cell growth and lipid content in Tetraselmis suecica, Dunaliella tertiolecta, Phaeodactylum tricornutum and Nannochloropsis oceanic. Exposure to LDR chronic irradiation increased cell density, specific growth rate and biomass in four microalgae strains. Furthermore, T. suecica, D. tertiolecta and P. tricornutum enhanced the lipid-specific BODIPY fluorescence intensity dependent on low-dose-rate irradiation. In particular, T. suecica showed the highest increase ratio of biomass and lipid content in 6 mGy h−1. These results suggest that LDR chronic irradiation induces enhancement of biomass and lipid content of marine microalgae.