Continuous Culture of Botryococcus braunii for Hydrocarbons Production

Abstract

Botryococcus braunii is a green, colonial microalga that can produce up to 75% of its dry weight as liquid hydrocarbons that can be converted easily in fuel. In order to cultivate Botryococcus braunii on commercial scale for the biofuel industry, new cultivation methods must be investigated. Until now, no studies have been performed on continuous culture of Botryococcus braunii under a photoperiod (cyclostat mode). The objective of this work is to investigate if the microalga can produce a constant amount of biomass and hydrocarbons in continuous culture under a light/dark cycle. Botryococcus braunii was grown in a stirred tank photobioreactor in continuous culture under a photoperiod of 12 h light and 12 h dark and using warm white LED light and red/blue LED light as light source with intensity of 442 µE m-2 s-1, and compared to continuous and batch culture. Results show that Botryococcus braunii in continuous culture under a photoperiod and in warm white LED light can produce a constant amount of dry biomass and hydrocarbons. Conversely Botryococcus braunii was not able to produce a constant amount of hydrocarbons and dry biomass in red/blue LED light.