Enhancement of lipid productivity by adopting multi-stage continuous cultivation strategy in Nannochloropsis gaditana.

In the present study, a novel process-based cultivation system was designed to improve lipid productivity of Nannochloropsis gaditana, an oleaginous microalga that has high potential for biofuel production. Specifically, four flat-panel photobioreactors were connected in series, and this system was subjected to continuous chemostat cultivation by feeding fresh medium to the first reactor at dilution rates of 0.028 and 0.056day-1, which were determined based on Monod kinetics. The results show that the serially connected photobioreactor system achieved 20.0% higher biomass productivity and 46.1% higher fatty acid methyl ester (FAME) productivity than a conventional single photobioreactor with equivalent dilution rate. These results suggest that a process-based approach using serially connected photobioreactors for microalgal cultivation can improve the productivity of lipids that can be used for biofuel production.