August 14, 2013

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Botryococcus braunii cultivation. © Kenji Imou.

The green colonial microalga Botryococcus braunii produces large amounts of hydrocarbons and accumulates them in an extracellular matrix, making it a target of research as a potential source of biofuel. Even though these hydrocarbons are accumulated in an external matrix, in general pretreatment such as drying or heating of wet algae followed by extraction using organic solvents is needed for sufficient recovery of hydrocarbons from B. braunii.

Prof. Imou's group at the Graduate School of Agricultural and Life Sciences have found that more than 90% of the accumulated hydrocarbons were readily extracted from B. braunii by simply mixing intact wet algal culture with an organic solvent such as n -hexane and without any pretreatment after culturing this freshwater alga in media with a salinity corresponding to 1/4 seawater for a certain period.

This finding indicates the potential for "milking" of hydrocarbons from the alga. If continuous recovery of hydrocarbons consecutively produced by living B. braunii maintained at high cell concentrations in the media becomes possible, problems caused by introducing contaminants into a large-size culture system of the alga could be prevented, and energy and costs for hydrocarbon production with the alga may be reduced.

This research was supported by Tokyo Gas Co. Ltd.

Paper Information

Kenichi Furuhashi, Kiyotaka Saga, Shigeru Okada, Kenji Imou, "Seawater-Cultured Botryococcus braunii for Efficient Hydrocarbon Extraction," PLoS ONE (2013) Vol.8, Issue.6, e66483, doi: 10.1371/journal.pone.0066483.