Bicarbonate-based cultivation of Dunaliella salina for enhancing carbon utilization efficiency

In this study, bicarbonate was proposed as an alternative carbon source to overcome exceedingly low CO2 fixation efficiency of conventional microalgae cultivation system. 5 g L−1 of sodium bicarbonate was found to well support the growth of Dunaliella salina, showing 2.84-fold higher specific growth rate than a bicarbonate-free control. This bicarbonate-fed cultivation also could yield biomass productivity similar to that of CO2-based system as long as pH was controlled. While the supplied CO2, because of its being a gas, was mostly lost and only 3.59% of it was used for biomass synthesis, bicarbonate was effectively incorporated into the biomass with 91.40% of carbon utilization efficiency. This study showed that the bicarbonate-based microalgae cultivation is indeed possible, and can even become a truly environment-friendly and workable approach, provided that a CO2 mineralization technology is concomitantly established.