title: Low-cost production of green microalga Botryococcus braunii biomass with high lipid content through mixotrophic and photoautotrophic cultivation.
abstract: Botryococcus braunii is a microalga that is regarded as a potential source of renewable fuel because of its ability to produce large amounts of lipid that can be converted into biodiesel. Agro-industrial by-products and wastes are of great interest as cultivation medium for microorganisms because of their low cost, renewable nature, and abundance. In this study, two strategies for low-cost production of B. braunii biomass with high lipid content were performed: (i) the mixotrophic cultivation using molasses, a cheap by-product from the sugar cane plant as a carbon source, and (ii) the photoautotrophic cultivation using nitrate-rich wastewater supplemented with CO2 as a carbon source. The mixotrophic cultivation added with 15 g L(-1) molasses produced a high amount of biomass of 3.05 g L(-1) with a high lipid content of 36.9 %. The photoautotrophic cultivation in nitrate-rich wastewater supplemented with 2.0 % CO2 produced a biomass of 2.26 g L(-1) and a lipid content of 30.3 %. The benefits of this photoautotrophic cultivation are that this cultivation would help to reduce accumulation of atmospheric carbon dioxide and more than 90 % of the nitrate could be removed from the wastewater. When this cultivation was scaled up in a stirred tank photobioreactor and run with semi-continuous cultivation regime, the highest microalgal biomass of 5.16 g L(-1) with a comparable lipid content of 32.2 % was achieved. These two strategies could be promising ways for producing cheap lipid-rich microalgal biomass that can be used as biofuel feedstocks and animal feeds.
authors.affiliation: Department of Industrial Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat-Yai, 90112, Thailand.
authors.forename: Chittra
authors.initials: C
authors.lastname: Yeesang
authors.forename: Benjamas
authors.initials: B
authors.lastname: Cheirsilp
mesh_terms: D056804:Biofuels; D018533:Biomass; D019149:Bioreactors; D000460:Chlorophyta / Q000254:growth & development*; D008965:Molasses
chemical_list: D056804:Biofuels