Open AccessConstruction of plasmid-free Escherichia coli for the production of arabitol-free xylitol from corncob hemicellulosic hydrolysate
Author(s) -
Buli Su,
Zhe Zhang,
Mianbin Wu,
Jianping Lin,
Lirong Yang
Publication year - 2016
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/srep26567
Subject(s) - xylitol , arabitol , corncob , hydrolysate , xylose , plasmid , pediococcus acidilactici , fermentation , chemistry , biochemistry , escherichia coli , biology , food science , hydrolysis , bacteria , gene , raw material , organic chemistry , lactic acid , genetics , lactobacillus plantarum
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.