title: Enhanced production of L-sorbose from D-sorbitol by improving the mRNA abundance of sorbitol dehydrogenase in Gluconobacter oxydans WSH-003.
abstract: BACKGROUND
  Production of L-sorbose from D-sorbitol by Gluconobacter oxydans is the first step to produce L-ascorbic acid on industrial scale. The sldhAB gene, which encodes the sorbitol dehydrogenase (SLDH), was overexpressed in an industrial strain G. oxydans WSH-003 with a strong promoter, P tufB . To enhance the mRNA abundance, a series of artificial poly(A/T) tails were added to the 3'-terminal of sldhAB gene. Besides, their role in sldhAB overexpression and their subsequent effects on L-sorbose production were investigated.
  
  
  RESULTS
  The mRNA abundance of the sldhAB gene could be enhanced in G. oxydans by suitable poly(A/T) tails. By self-overexpressing the sldhAB gene in G. oxydans WSH-003 with an optimal poly(A/T) tail under the constitutive promoter P tufB , the titer and the productivity of L-sorbose were enhanced by 36.3% and 25.0%, respectively, in a 1-L fermenter. Immobilization of G. oxydans-sldhAB6 cells further improved the L-sorbose titer by 33.7% after 20 days of semi-continuous fed-batch fermentation.
  
  
  CONCLUSIONS
  The artificial poly(A/T) tails could significantly enhance the mRNA abundance of the sldhAB. Immobilized G. oxydans-sldhAB6 cells could further enlarge the positive effect caused by enhanced mRNA abundance of the sldhAB.
authors.affiliation: School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. xus1984@gmail.com.
authors.forename: Sha
authors.initials: S
authors.lastname: Xu
authors.affiliation: School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. 304686837@qq.com.
authors.forename: Xiaobei
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. gcdu@jiangnan.edu.cn.|Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. gcdu@jiangnan.edu.cn.
authors.forename: Guocheng
authors.initials: G
authors.lastname: Du
authors.affiliation: School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. zhoujw1982@jiangnan.edu.cn.|Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. zhoujw1982@jiangnan.edu.cn.
authors.forename: Jingwen
authors.initials: J
authors.lastname: Zhou
authors.affiliation: School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. jchen@jiangnan.edu.cn.|Synergetic Innovation Center of Food Safety and Nutrition, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China. jchen@jiangnan.edu.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D020600:Gluconobacter oxydans / Q000235:genetics / Q000378:metabolism; D007064:L-Iditol 2-Dehydrogenase / Q000096:biosynthesis / Q000235:genetics; D011401:Promoter Regions, Genetic; D020871:RNA Stability; D012329:RNA, Bacterial / Q000096:biosynthesis / Q000235:genetics; D013012:Sorbitol / Q000378:metabolism*; D013013:Sorbose / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D013012:Sorbitol; D007064:L-Iditol 2-Dehydrogenase; D013013:Sorbose