A screening method using 15% CO 2 (v/v) as screening stress and a spotting plate method was developed to isolate microalgae with the potential to convert flue gas CO 2 to biomass. A total of six microalgal strains, belonging to the genera Chlorella , Heynigia , Desmodesmus , and Scenedesmus , were isolated from ponds near metallurgical/cement/power plants. The growth of these isolated strains was dramatically promoted at 5 to 15% CO 2 when they were cultivated in bubble column photobioreactors aerating with 0.03%, 5%, 10%, and 15% CO 2 . The growth of Heynigia riparia SX01 in particular showed substantial improvement with the increase of CO 2 concentrations from 5 to 15%. Furthermore, the maximum biomass, overall biomass productivity, maximum biomass productivity, and maximum CO 2 fixation rate of these microalgal strains greatly increased at 5 to 15% CO 2 as well. Chlorella sorokiniana GS03 showed the highest values in maximum biomass productivity (0.36 g L −1  day −1 ) and maximum CO 2 fixation rate (0.66 g L −1  day −1 ) at 5% CO 2 . Heynigia riparia SX01 exhibited the highest values of maximum biomass (3.28 g L −1 ), overall biomass productivity (0.27 g L −1  day −1 ), maximum biomass productivity (0.39 g L −1  day −1 ), and maximum CO 2 fixation rate (0.71 g L −1  day −1 ) at 15% CO 2 . This study provides not only an efficient screening method obtaining microalgae with wide CO 2 tolerance but also microalgal strains utilizing high levels of CO 2 up to 15% to produce biomass, which contributes to further exploration in converting real flue gas CO 2 into biomass feedstock.