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. 5gL^-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.