Cultivation of Botryococcus braunii Showa in Annular Columns and Green Wall Panel reactors up to 1400 L

Botryococcus braunii is a colonial green alga that is classified in different races (A, B, L) on the basis of the main hydrocarbon produced. This alga is attracting much interest mainly because of its ability to produce and release hydrocarbons of great value for biofuels, although it can also produce other biotechnologically relevant molecules, like other lipids and exopolysaccharides. The main problem with commercial exploitation of this alga is its low productivity. In this work B. braunii Showa (B race) was cultivated both indoors and outdoors. Indoors, cultivation was performed in 60-L annular columns, reaching maximum biomass productivities of about 110 mg L -1 day -1 . The culture produced in the columns was used to inoculate 40-L GWP®-III reactors, which were operated outdoors. In this system biomass productivities attained values up to 210 mg L -1 day -1 . The cultures obtained here were used to inoculate a 1400-L GWP ® -II reactor. Maximum biomass productivities in this large pilot outdoors were about 140 mg L -1 day -1 . Hydrocarbon production and yields will be illustrated. The 40-L GWP ® reactor was also used to produce inoculum for two 1-m 2 raceway ponds, one of which was maintained under nutrient replete conditions and the other under nitrogen starvation. Biomass productivities were slightly higher under nutrient replete conditions, with maximum values of 160 compared to 140 mg L -1 day - 1 under N starvation. Effects on hydrocarbon production of nitrogen starvation will be presented. The main issues during cultivation were sensitivity to high light, to low temperature and to contamination.