title: Microfluidic high-throughput selection of microalgal strains with superior photosynthetic productivity using competitive phototaxis.
abstract: Microalgae possess great potential as a source of sustainable energy, but the intrinsic inefficiency of photosynthesis is a major challenge to realize this potential. Photosynthetic organisms evolved phototaxis to find optimal light condition for photosynthesis. Here we report a microfluidic screening using competitive phototaxis of the model alga, Chlamydomonas reinhardtii, for rapid isolation of strains with improved photosynthetic efficiencies. We demonstrated strong relationship between phototaxis and photosynthetic efficiency by quantitative analysis of phototactic response at the single-cell level using a microfluidic system. Based on this positive relationship, we enriched the strains with improved photosynthetic efficiency by isolating cells showing fast phototactic responses from a mixture of 10,000 mutants, thereby greatly improving selection efficiency over 8 fold. Among 147 strains isolated after screening, 94.6% showed improved photoautotrophic growth over the parental strain. Two mutants showed much improved performances with up to 1.9- and 8.1-fold increases in photoautotrophic cell growth and lipid production, respectively, a substantial improvement over previous approaches. We identified candidate genes that might be responsible for fast phototactic response and improved photosynthesis, which can be useful target for further strain engineering. Our approach provides a powerful screening tool for rapid improvement of microalgal strains to enhance photosynthetic productivity.
authors: Department of Chemical and Biological Engineering, Korea University, Seoul, 136-713, Republic of Korea.
authors: Jaoon Young Hwan
authors: JY
authors: Kim
authors: Department of Chemical and Biological Engineering, Korea University, Seoul, 136-713, Republic of Korea.
authors: Ho Seok
authors: HS
authors: Kwak
authors: Department of Chemical and Biological Engineering, Korea University, Seoul, 136-713, Republic of Korea.
authors: Young Joon
authors: YJ
authors: Sung
authors: Department of Chemical and Biological Engineering, Korea University, Seoul, 136-713, Republic of Korea.
authors: Hong Il
authors: HI
authors: Choi
authors: Department of Chemical and Biological Engineering, Korea University, Seoul, 136-713, Republic of Korea.
authors: Min Eui
authors: ME
authors: Hong
authors: Department of Chemical and Biological Engineering, Korea University, Seoul, 136-713, Republic of Korea.
authors: Hyun Seok
authors: HS
authors: Lim
authors: Department of Botany, University of British Columbia, Vancouver, V6T1Z4, Canada.
authors: Jae-Hyeok
authors: JH
authors: Lee
authors: Department of Chemical and Biomolecular Engineering (BK21 Plus Program), BioProcess Engineering Research Center, Bioinformatics Research Center, Center for Systems and Synthetic Biotechnology, Institute for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea.
authors: Sang Yup
authors: SY
authors: Lee
authors: Department of Chemical and Biological Engineering, Korea University, Seoul, 136-713, Republic of Korea.|Green School, Korea University, Seoul, 136-713, Republic of Korea.
authors: Sang Jun
authors: SJ
authors: Sim
mesh_terms: D056804:Biofuels / Q000382:microbiology; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology; D008027:Light; D058086:Microalgae / Q000235:genetics / Q000378:metabolism*; D044085:Microfluidics / Q000295:instrumentation / Q000379:methods*; D010788:Photosynthesis / Q000502:physiology*; D000071444:Phototaxis / Q000502:physiology*
chemical_list: D056804:Biofuels; D002734:Chlorophyll