title: Metabolic engineering of Clostridium tyrobutyricum for n-butanol production through co-utilization of glucose and xylose.
abstract: The glucose-mediated carbon catabolite repression (CCR) in Clostridium tyrobutyricum impedes efficient utilization of xylose present in lignocellulosic biomass hydrolysates. In order to relieve the CCR and enhance xylose utilization, three genes (xylT, xylA, and xylB) encoding a xylose proton-symporter, a xylose isomerase and a xylulokinase, respectively, from Clostridium acetobutylicum ATCC 824 were co-overexpressed with aldehyde/alcohol dehydrogenase (adhE2) in C. tyrobutyricum (Δack). Compared to the strain Ct(Δack)-pM2 expressing only adhE2, the mutant Ct(Δack)-pTBA had a higher xylose uptake rate and was able to simultaneously consume glucose and xylose at comparable rates for butanol production. Ct(Δack)-pTBA produced more butanol (12.0 vs. 3.2 g/L) with a higher butanol yield (0.12 vs. 0.07 g/g) and productivity (0.17 vs. 0.07 g/L · h) from both glucose and xylose, while Ct(Δack)-pM2 consumed little xylose in the fermentation. The results confirmed that the CCR in C. tyrobutyricum could be overcome through overexpressing xylT, xylA, and xylB. The mutant was also able to co-utilize glucose and xylose present in soybean hull hydrolysate (SHH) for butanol production, achieving a high butanol titer of 15.7 g/L, butanol yield of 0.24 g/g, and productivity of 0.29 g/L · h. This study demonstrated the potential application of Ct(Δack)-pTBA for industrial biobutanol production from lignocellulosic biomass.
authors.affiliation: William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Ave., Columbus, Ohio, 43210.
authors.forename: Le
authors.initials: L
authors.lastname: Yu
authors.affiliation: William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Ave., Columbus, Ohio, 43210.
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Xu
authors.affiliation: Bioprocessing Innovative Company, Dublin, Ohio.
authors.forename: I-Ching
authors.initials: IC
authors.lastname: Tang
authors.affiliation: William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Ave., Columbus, Ohio, 43210. yang.15@osu.edu.
authors.forename: Shang-Tian
authors.initials: ST
authors.lastname: Yang
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D046969:Clostridium acetobutylicum / Q000201:enzymology / Q000235:genetics; D048014:Clostridium tyrobutyricum / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D017353:Gene Deletion; D015870:Gene Expression; D005947:Glucose / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013025:Glycine max / Q000378:metabolism; D014994:Xylose / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D020001:1-Butanol; D014994:Xylose; D005947:Glucose
keywords: Clostridium tyrobutyricum; butanol; carbon catabolite repression; metabolic engineering; soybean hull hydrolysate; xylose