Photobioreactor-based procedures for reproducible small-scale production of microalgal biomasses

International audienceA simply designed photobioreactor (PBR) was developed with associated microalga production protocols for Arthrospira platensis and Chlorella vulgaris. 80-L culture medium batches of unstressed microalgal strains, still in their growing phase, were obtained. For the two microalgal strains used, biomass production cycles were found to be reproducible between replicate runs. On a dry weight basis (d.w.), productivity (P) and total biomass production (TBP) at the end of a production cycle (30 days) were respectively 30 mg d.w. L-1 day -1 and 0.9 g d.w.L-1 for Spirulina, and 20 mg d.w. L-1 day -1 and 0.6 g d.w. L-1 for Chlorella. Four sets of fluorescent light blocks (72 W) symmetrically set around the PBR tube provided the culture medium with permanent illumination of 336 μmol m-2 s-1 for Spirulina, and 168 μmol m-2 s-1 for Chlorella. The unsophisticated design of this PBR unit makes it suitable for use in low-level technical environments, generally found in developing countries such as Côte d’Ivoire. The production protocols described enable even unskilled people to produce themselves these two microalgal biomasses that are locally used as food or feed supplements, or as partial substitutes for commercial fish feed used to raise tropical fish such as tilapia (Sarotherodon melanotheron), in small-scale recirculation breeding systems