title: Photosynthesis-fermentation hybrid system to produce lipid feedstock for algal biofuel.
abstract: To avoid bacterial contamination due to medium replacement in the expanded application of a photosynthesis-fermentation model, an integrated photosynthesis-fermentation hybrid system was set up and evaluated for algal lipid production using Chlorella protothecoides. In this system, the CO2-rich off-gas from the fermentation process was recycled to agitate medium in thephotobioreactor, which could provide initial cells for the heterotrophic fermentation. The cell concentration reached 1.03 +/- 0.07 g/L during photoautotrophic growth and then the concentrated green cells were switched to heterotrophic fermentation after removing over 99.5% ofnitrogen in the medium by a nitrogen removal device. At the end offermentation in the system, the cell concentration could reach as high as 100.51 +/- 2.03 g/L, and 60.05 +/- 1.38% lipid content was achieved simultaneously. The lipid yield (60.36 +/- 2.63 g/L) in the hybrid system was over 700 times higher than that in a photobioreactor and exceeded that by fermentation alone (47.56 +/- 7.31 g/L). The developed photosynthesis-fermentation hybrid system in this study was not only a feasible option to enhance microalgal lipid production, but also an environment-friendly approach to produce biofuel feedstock through concurrent utilization of ammonia nitrogen, CO2, and organic carbons.
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Lu
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Junbiao
authors.initials: J
authors.lastname: Dai
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Wu
mesh_terms: D056804:Biofuels; D002708:Chlorella / Q000737:chemistry / Q000378:metabolism*; D005285:Fermentation; D008055:Lipids / Q000032:analysis / Q000096:biosynthesis*; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D058433:Photobioreactors; D010788:Photosynthesis
chemical_list: D056804:Biofuels; D008055:Lipids; D009584:Nitrogen