报告摘要

Microalgae have emerged as excellent platforms for production biofuels and other chemicals that can replace current fossil fuels. However, they are currently in the state of "wild" and thus require extensive genetic and biological engineering for optimum performance in the production line. We are devoted to improve industrial microalgae by employing the age-old concepts of domestication process that have been used for crop plants, including mutagenesis and polyploidization. We also use state-of-the-art technologies including transcription factor (TF) engineering, gene editing, and metabolic engineering. Among these, TF engineering allowed us to improve industrial microalga Nannochloropsis salina for increased production of biomass and lipids. These strains were further tested for scale-up and continuous cultivation in PBR, revealing potentials that they can be utilized for production of biofuels and other biomaterials. In addition, we obtained a mutant (E5) that showed reduced light harvesting antenna complex (LHC) in Chlorella vulgaris. E5 grew better under high light conditions compared to WT, and molecular analyses revealed that E5 was defective in the antenna complex with improved photosynthetic efficiency and reduced non-photochemical quenching (NPQ). Genome sequencing of E5 revealed a point mutation in a gene encoding chloroplast signal recognition particle 43 (CpSRP43), well known for its function in antennal assembly in Chlamydomonas and plants. Complementation assay proved that this mutation was responsible for E5 phenotypes. We are also interested in improving photosynthetic efficiency by heterologous synthesis of chlorophyll b in N. salina that lacks any accessory chlorophylls. By expression of Chlamydomonas chlorophyllide a oxygenase (CrCAO), we created Nannochloropsis lines that produced Chlb for the first time. These lines showed improved growth and photosynthetic efficiency, and excitingly increased yield of lipids. Taken together, we have provided applicable proof of the concept that TFs and photosynthetic components can be engineered for improved production of biomass and biomaterials in industrial microalgae.
 
报告人简介

Prof. Byeong-ryool "BJ" Jeong is a distinguished phycologist working on algae biology and biotechnology. He received his BS (1983) and MSc (1985) from Pusan National University, South Korea (1973), and his PhD (1998) from Indiana University, USA, followed by a postdoc (1998-2004) and Research Assistant professor (2005-2011) at University of Nebraska-Lincoln, USA. BJ has been a Research professor at Korea Advanced Institute of Science and Technology (KAIST) since 2013. His group has broad research interests including 1) photosynthesis, 2) lipid metabolism, 3) genetic engineering of production strains of algae, 4) stress and pathology, etc, with many publications in top journals such as PNAS, J Biol Chem, Biotech Biofuels and Biotech Bioeng.