Cyanobacterial photo-driven mixotrophic metabolism and its advantages for biosynthesis  

作　　者：Ni Wan Mary Abernathy Joseph Kuo-Hsiang Tang Yinjie J. Tang Le You 

机构地区：[1]Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO 63130, USA [2]Biodesign Institute, Arizona State University, Tempe, AZ 85281, USA

出　　处：《Frontiers of Chemical Science and Engineering》2015年第3期308-316,共9页化学科学与工程前沿（英文版）

摘　　要：Cyanobacterium offers a promising chassis for phototrophic production of renewable chemicals. Although engineered cyanobacteria can achieve similar product carbon yields as heterotrophic microbial hosts, their production rate and titer under photoautotrophic conditions are 10 to 100 folds lower than those in fast growing E. colt. Cyanobacterial factories face three indomitable bottlenecks. First, photosynthesis has limited ATP and NADPH generation rates. Second, CO2 fixation by ribulose-l,5-bisphosphate carboxylase/oxygenase （RuBisCO） has poor efficiency. Third, CO2 mass transfer and light supply are deficient within large photobioreac- tors. On the other hand, cyanobacteria may employ organic substrates to promote phototrophic cell growth, Nz fixation, and metabolite synthesis. The photo-fermenta- tions show enhanced photosynthesis, while CO2 loss from organic substrate degradation can be reused by the Calvin cycle. In addition, the plasticity of cyanobacterial path- ways （e.g., oxidative pentose phosphate pathway and the TCA cycle） has been recently revealed to facilitate the catabolism. The use of cyanobacteria as ＂green E. colt＂ could be a promising route to develop robust photobiorefineries.Cyanobacterium offers a promising chassis for phototrophic production of renewable chemicals. Although engineered cyanobacteria can achieve similar product carbon yields as heterotrophic microbial hosts, their production rate and titer under photoautotrophic conditions are 10 to 100 folds lower than those in fast growing E. colt. Cyanobacterial factories face three indomitable bottlenecks. First, photosynthesis has limited ATP and NADPH generation rates. Second, CO2 fixation by ribulose-l,5-bisphosphate carboxylase/oxygenase （RuBisCO） has poor efficiency. Third, CO2 mass transfer and light supply are deficient within large photobioreac- tors. On the other hand, cyanobacteria may employ organic substrates to promote phototrophic cell growth, Nz fixation, and metabolite synthesis. The photo-fermenta- tions show enhanced photosynthesis, while CO2 loss from organic substrate degradation can be reused by the Calvin cycle. In addition, the plasticity of cyanobacterial path- ways （e.g., oxidative pentose phosphate pathway and the TCA cycle） has been recently revealed to facilitate the catabolism. The use of cyanobacteria as ＂green E. colt＂ could be a promising route to develop robust photobiorefineries.

关 键 词：CO2 mass transfer N2 fixation PHOTOSYSTEM RUBISCO the TCA cycle 

分 类 号：Q949.22[生物学—植物学] TQ465.5[化学工程—制药化工]