【Abstract】 The effects of CO₂ concentration on the growth and photosynthesis of Dicrateria zhangjiangensis and Dunaliella sp.in 100 liter air lift photobioreactors were investigated. The results showed that biomass of both algae significantly increased in high CO₂ concentration (above 700μL·L^-1 ) compared to low CO₂ concentration(350μL·L^-1),and the culture periods were shorter. However, no significant difference as observed in growth rate when the alga cultured in CO₂ concentration of 700μL·L^-1 and 1000μL·L^-1, respectively. These for the maximum photosynthetic rate（Pm） and saturating irradiance level（Ik） of the two species remarkably raised with the elevated CO₂ concentration, so was the initial slope（α）of Dunaliella sp.更多还原