title: Metabolic engineering of Clostridium tyrobutyricum for n-butanol production: effects of CoA transferase.
abstract: The overexpression of CoA transferase (ctfAB), which catalyzes the reaction: acetate/butyrate + acetoacetyl-CoA → acetyl/butyryl-CoA + acetoacetate, was studied for its effects on acid reassimilation and butanol biosynthesis in Clostridium tyrobutyricum (Δack, adhE2). The plasmid pMTL007 was used to co-express adhE2 and ctfAB from Clostridium acetobutylicum ATCC 824. In addition, the sol operon containing ctfAB, adc (acetoacetate decarboxylase), and ald (aldehyde dehydrogenase) was also cloned from Clostridium beijerinckii NCIMB 8052 and expressed in C. tyrobutyricum (Δack, adhE2). Mutants expressing these genes were evaluated for their ability to produce butanol from glucose in batch fermentations at pH 5.0 and 6.0. Compared to C. tyrobutyricum (Δack, adhE2) without expressing ctfAB, all mutants with ctfAB overexpression produced more butanol, with butanol yield increased to 0.22 - 0.26 g/g (vs. 0.10 - 0.13 g/g) and productivity to 0.35 g/l h (vs. 0.13 g/l h) because of the reduced acetate and butyrate production. The expression of ctfAB also resulted in acetone production from acetoacetate through a non-enzymatic decarboxylation.
authors: William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Ave., Columbus, OH, 43210, USA.
authors: Le
authors: L
authors: Yu
authors: Jingbo
authors: J
authors: Zhao
authors: Mengmeng
authors: M
authors: Xu
authors: Jie
authors: J
authors: Dong
authors: Saju
authors: S
authors: Varghese
authors: Mingrui
authors: M
authors: Yu
authors: I-Ching
authors: IC
authors: Tang
authors: Shang-Tian
authors: ST
authors: Yang
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D000096:Acetone / Q000378:metabolism; D046969:Clostridium acetobutylicum / Q000201:enzymology / Q000235:genetics; D046970:Clostridium beijerinckii / Q000201:enzymology / Q000235:genetics; D048014:Clostridium tyrobutyricum / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D015256:Coenzyme A-Transferases / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D017353:Gene Deletion; D015870:Gene Expression; D005947:Glucose / Q000378:metabolism; D060847:Metabolic Engineering; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D010957:Plasmids
chemical_list: D000096:Acetone; D020001:1-Butanol; D015256:Coenzyme A-Transferases; D005947:Glucose