title: Construction of plasmid-free Escherichia coli for the production of arabitol-free xylitol from corncob hemicellulosic hydrolysate.
abstract: High costs and low production efficiency are a serious constraint to bio-based xylitol production. For industrial-scale production of xylitol, a plasmid-free Escherichia coli for arabitol-free xylitol production from corncob hemicellulosic hydrolysate has been constructed. Instead of being plasmid and inducer dependent, this strain relied on multiple-copy integration of xylose reductase (XR) genes into the chromosome, where their expression was controlled by the constitutive promoter P43. In addition, to minimize the flux from L-arabinose to arabitol, two strategies including low XR total activity and high selectivity of XR has been adopted. Arabitol was significantly decreased using plasmid-free strain which had lower XR total activity and an eight point-mutations of XR with a 27-fold lower enzyme activity toward L-arabinose was achieved. The plasmid-free strain in conjunction with this mutant XR can completely eliminate arabitol formation in xylitol production. In fed-batch fermentation, this plasmid-free strain produced 143.8 g L(-1) xylitol at 1.84 g L(-1) h(-1) from corncob hemicellulosic hydrolysate. From these results, we conclude that this route by plasmid-free E. coli has potential to become a commercially viable process for xylitol production.
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Buli
authors.initials: B
authors.lastname: Su
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Mianbin
authors.initials: M
authors.lastname: Wu
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Lin
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Lirong
authors.initials: L
authors.lastname: Yang
mesh_terms: D000449:Aldehyde Reductase / Q000235:genetics*; D001089:Arabinose / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D005285:Fermentation; D005656:Fungal Proteins / Q000235:genetics; D006868:Hydrolysis; D060847:Metabolic Engineering; D009492:Neurospora crassa / Q000201:enzymology* / Q000235:genetics; D010957:Plasmids; D011401:Promoter Regions, Genetic; D013402:Sugar Alcohols / Q000378:metabolism; D014993:Xylitol / Q000378:metabolism*; D003313:Zea mays / Q000737:chemistry*
chemical_list: D005656:Fungal Proteins; D013402:Sugar Alcohols; D001089:Arabinose; D000449:Aldehyde Reductase; D014993:Xylitol; C014999:arabitol