The effect of media on biomass and oil production in Botryococcus braunii strains Kossou-4 and Overjuyo-3

The green algae Botryococcus braunii is widely recognized as a source of oil, including hydrocarbons. However, the slow rate of growth B. braunii hampers its commercial development. This study addresses this by examining the effects of three growth media on biomass and oil production in two B. braunii Race B strains, Kossou-4 and Overjuyo-3. Growth of B. braunii strains in BG11 medium resulted in significantly higher growth (2.3 - 4.2 and 2.9 - 6.0 fold increases in Kossou-4 and Overjuyo-3 respectively) compared to the JM and BBM-3N media after 15 days. A similar trend was obtained when biomass was measured indirectly using optical density (OD) and chlorophyll fluorescence. Oil production was also significantly higher in BG11 whether measured as oil weight or absorbance (ODs at 680 and 750 nm). However, the presence of extracellular oil was shown to increase absorbance values making OD measurements less reliable than dry weight assays. Maximum recovery of oil was recorded when hexane was used as solvent compared to hexane-isopropanol and heptane. These results suggest that BG11 is the best growth medium for these two strains under the conditions of this experiment.