Dual-mode cultivation of Chlorella protothecoides applying inter-reactors gas transfer improves microalgae biodiesel production

• Published in: Journal of biotechnology Vol. 184; pp. 74 - 83
• Main Authors: Santos, C.A., Nobre, B., Lopes da Silva, T., Pinheiro, H.M., Reis, A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.08.2014
• Subjects: Autotrophic; Biodiesel; Biofuels; Biomass; Carbon dioxide; Carbon Dioxide - metabolism; Carbon dioxide fixation; Chlorella - growth & development; Chlorella - metabolism; Chlorella protothecoides; Fatty acids; Fatty Acids - biosynthesis; Gases; Heterotrophic; Heterotrophic Processes; Lipids - biosynthesis; Microalgae - growth & development; Microalgae - metabolism; Productivity; Reactors; Carbon dioxide fixation; Heterotrophic; Chlorella protothecoides; Biodiesel; Autotrophic
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/j.jbiotec.2014.05.012

•Setup of fermenter connected to photobioreactor improves microalga productivity.•Enhancement of microalga growth by CO2 from off-gases fermentation.•Efficient CO2 fixation by autotrophic Chlorella protothecoides.•Lutein and lipids source to produce high value product and biodiesel, respectively.•Bioreactors association is a feasible way to restore O2 spent in fermentation. Chlorella protothecoides, a lipid-producing microalga, was grown heterotrophically and autotrophically in separate reactors, the off-gases exiting the former being used to aerate the latter. Autotrophic biomass productivity with the two-reactor association, 0.0249gL−1h−1, was 2.2-fold the value obtained in a control autotrophic culture, aerated with ambient air. Fatty acid productivity was 1.7-fold the control value. C. protothecoides heterotrophic biomass productivity was 0.229gL−1h−1. This biomass’ fatty acid content was 34.5% (w/w) with a profile suitable for biodiesel production, according to European Standards. The carbon dioxide fixed by the autotrophic biomass was 45mgCO2L−1h−1 in the symbiotic arrangement, 2.1 times the control reactor value. The avoided CO2 atmospheric emission represented 30% of the CO2 produced in the heterotrophic stage, while the released O2 represented 49% of the oxygen demand in that stage. Thus, an increased efficiency in the glucose carbon source use and a higher environmental sustainability were achieved in microalgal biodiesel production using the proposed assembly.