title: Optimization of isopropanol production by engineered cyanobacteria with a synthetic metabolic pathway.
abstract: 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).
authors.affiliation: Laboratory for Bioinformatics, Graduate School of Systems Biosciences, Kyushu University, 804 Westwing, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Hirokawa
authors.affiliation: Laboratory of Plant Physiology and Metabolism, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba 305-8572, Japan.
authors.forename: Iwane
authors.initials: I
authors.lastname: Suzuki
authors.affiliation: Laboratory for Bioinformatics, Graduate School of Systems Biosciences, Kyushu University, 804 Westwing, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Electronic address: taizo@brs.kyushu-u.ac.jp.
authors.forename: Taizo
authors.initials: T
authors.lastname: Hanai
mesh_terms: D019840:2-Propanol / Q000378:metabolism*; D000085:Acetates / Q000378:metabolism; D000332:Aerobiosis; D000693:Anaerobiosis; D002021:Buffers; D000458:Cyanobacteria / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D003624:Darkness; D006863:Hydrogen-Ion Concentration; D008027:Light; D060847:Metabolic Engineering; D053858:Metabolic Networks and Pathways / Q000235:genetics* / Q000528:radiation effects
chemical_list: D000085:Acetates; D002021:Buffers; D019840:2-Propanol
keywords: Acetate utilization; Cyanobacteria; Dark and anaerobic condition; Isopropanol production; Synthetic metabolic pathway