The growth, lipid and hydrocarbon production of Botryococcus braunii with attached cultivation

Abstract

The green alga Botryococcus braunii is regarded as a potential source of renewable fuel due to its high lipid and hydrocarbon contents. However, the slow growth rate damaged its feasibility for biofuel production. In this study, a novel method of 'attached cultivation' was introduced to incubate B. braunii FACHB 357 (B race). A high biomass productivity of 6.5 gm(-2)d(-1) was achieved in single layer attached system at early stage of cultivation. At day 10, the biomass, lipid and hydrocarbon productivities were 5.5, 2.34 and 1.06 gm(-2)d(-1), respectively. Under nitrogen starvation condition, both of the contents of lipid and hydrocarbon were increased, whereas the profile of hydrocarbon kept almost unchanged, while the content for oleic acid (18:1) increased and linolenic acid (18:3) decreased. With a multi-layer photobioreactor, a biomass productivity of 49.1 gm(-2)d(-1) or a photosynthetic efficiency of 14.9% (visible light) were obtained under continuous illumination of 500 μmolm(-2)s(-1).