title: Double CO(2) fixation in photosynthesis-fermentation model enhances algal lipid synthesis for biodiesel production.
abstract: In this study, a photosynthesis-fermentation model was proposed to merge the positive aspects of autotrophs and heterotrophs. Microalga Chlorella protothecoides was grown autotrophically for CO(2) fixation and then metabolized heterotrophically for oil accumulation. Compared to typical heterotrophic metabolism, 69% higher lipid yield on glucose was achieved at the fermentation stage in the photosynthesis-fermentation model. An elementary flux mode study suggested that the enzyme Rubisco-catalyzed CO(2) re-fixation, enhancing carbon efficiency from sugar to oil. This result may explain the higher lipid yield. In this new model, 61.5% less CO(2) was released compared with typical heterotrophic metabolism. Immunoblotting and activity assay further showed that Rubisco functioned in sugar-bleaching cells at the fermentation stage. Overall, the photosynthesis-fermentation model with double CO(2) fixation in both photosynthesis and fermentation stages, enhances carbon conversion ratio of sugar to oil and thus provides an efficient approach for the production of algal lipid.
authors: Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, PR China.
authors: Wei
authors: W
authors: Xiong
authors: Chunfang
authors: C
authors: Gao
authors: Dong
authors: D
authors: Yan
authors: Chao
authors: C
authors: Wu
authors: Qingyu
authors: Q
authors: Wu
mesh_terms: D056804:Biofuels / Q000382:microbiology*; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D002245:Carbon Dioxide / Q000378:metabolism*; D002708:Chlorella / Q000166:cytology / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D005285:Fermentation / Q000502:physiology*; D005742:Gasoline / Q000382:microbiology; D052836:Heterotrophic Processes; D008055:Lipids / Q000096:biosynthesis*; D053858:Metabolic Networks and Pathways; D008954:Models, Biological; D010788:Photosynthesis / Q000502:physiology*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism
chemical_list: D056804:Biofuels; D005742:Gasoline; D008055:Lipids; D002734:Chlorophyll; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase