Botryococcus braunii strain Showa in annular photobioreactors under artificial light

Botryococcus braunii strain Showa (race B) is a green microalga able to release long chain hydrocarbons, suitable for use as energy-rich compounds for biofuel applications, but also for high-value markets, like cosmetics. Its ability to grow in annular reactors up to 60 L was investigated. As expected, biomass productivities were rather low, with a maximum aver- age of about 120 mg L −1   day −1 . Optimization of culture conditions (e.g., cell concentration, temperature, light period, light quality) is necessary to increase biomass productivity. The main weaknesses emerged were sensitivity to high light coupled to low temperatures and susceptibility to contamination by competing phototrophs. Hydrocarbon content was quite con- stant, reaching 26–28% of dry biomass, so hydrocarbon productivity was mainly determined by biomass productivity. The system proved to be suitable to grow B. braunii Showa to produce high quality inoculum, nevertheless for an economically sustainable large-scale production, even considering only high-value applications, higher biomass/component productivities would be necessary.