A Botryococcus Strain with Bacterial Ectosymbionts Grows Fast and Produces High Amount of Hydrocarbons

A Botyrococcus braunii strain with high potential for biofuel production was isolated from a pond in Southeast Asia. This strain showed a higher growth rate (μ= 0.101/day) and biomass productivity (2.61 dry cell weight (dcw) g/L), both of which are comparable to those of our benchmark strain B. braunii BOT-22. Chemical analyses indicated that this strain produced >44% of lipids (w/dcw), 21-37% of which was identified as C34 botryococcene. 18S rDNA sequence analysis indicated this strain is closely related to BOT-22, suggesting that this strain can be affiliated into Race B. Interestingly, microscopic observations revealed that this strain harboured numerous bacterial ectosymbionts at the rim of host Botryococcus colonies. Our results suggest that algal-bacterial symbiotic consortia may have a potential to improve the productivity of biofuels, providing us with an alternative to pure culture of oil-producing algae.