Optimization of isopropanol production by engineered cyanobacteria with a synthetic metabolic pathway

• Published in: Journal of bioscience and bioengineering Vol. 119; no. 5; pp. 585 - 590
• Main Authors: Hirokawa, Yasutaka, Suzuki, Iwane, Hanai, Taizo
• Format: Journal Article
• Language: English
• Published: Japan Elsevier B.V 01.05.2015
• Subjects: 2-Propanol - metabolism; Acetate utilization; Acetates - metabolism; Aerobiosis; Anaerobiosis; Buffers; Cyanobacteria; Cyanobacteria - genetics; Cyanobacteria - growth & development; Cyanobacteria - metabolism; Cyanobacteria - radiation effects; Dark and anaerobic condition; Darkness; Hydrogen-Ion Concentration; Isopropanol production; Light; Metabolic Engineering; Metabolic Networks and Pathways - genetics; Metabolic Networks and Pathways - radiation effects; Synthetic metabolic pathway; Acetate utilization; Dark and anaerobic condition; Isopropanol production; Synthetic metabolic pathway; Cyanobacteria
• ISSN: 1389-1723; 1347-4421
• DOI: 10.1016/j.jbiosc.2014.10.005

Cyanobacterium is an attractive host for the production of various chemicals and alternative fuels using solar energy and carbon dioxide. In previous study, we succeeded to produce isopropanol using engineered Synechococcus elongatus PCC 7942 under dark and anaerobic conditions (0.43 mM, 26.5 mg/l). In the present study, we report the further optimization of this isopropanol producing condition. We then optimized growth conditions for production of isopropanol by the engineered cyanobacteria, including the use of cells in early stationary phase and buffering of the production medium to neutral pH. We observed that shifting of cultures from dark and anaerobic to light and aerobic conditions during the production phase dramatically increased isopropanol production by conversion to isopropanol from acetate, byproduct under dark and anaerobic condition. Under the optimized production conditions, the titer of isopropanol was elevated 6-fold, to 2.42 mM (146 mg/l).