Cobalt enrichment enhances the tolerance of Botryococcus braunii to high concentration of CO₂

This work mainly studied B. braunii adapted to different CO₂ concentrations with cobalt enrichment, and developed a process for CO₂ capture, hydrocarbon production and cobalt removal. The results showed that B. braunii favored rapid growth at 5.0% (v/v) CO₂, and the highest biomass was 1.89 g.L⁻¹ with 4.5 mg.L⁻¹ of cobalt. Hydrocarbon productivity in high concentration CO₂ (5.0% and 10.0%) with cobalt enrichment was higher than that in Chu 13 medium. The change in cobalt removal efficiency mainly corresponded to the growth of B. braunii. The LCE of B. braunii in cobalt-rich with high CO₂ concentration (5.0% and 10.0%) was 15.7%, and 14.9%, respectively, which was higher than that in normal medium. CO₂ fixation rates were also higher in cobalt enrichment coupled with high CO₂ concentration. This study not only provides ideas for the removal of toxic metal cobalt, but also has great potential for CO₂ biofixation.