Institute of Microbiology
Chinese Academy of Sciences
Tel: 86-10-64807496
E-mail: jiangn@im.ac.cn

Research Area
Microbial carbohydrate metabolic engineering

Current Research
Microbial carbohydrate metabolic engineering is engaged in the development of commercial important microorganisms by means of metabolic engineering.  At present, the main research program is focused on the improvement of yeast strains, which can effectively ferment both glucose and xylose from lignocellulosic biomass to produce ethanol.  Also, the group has engineered other yeast strains to produce pyruvate and xylitol respectively.  Pyruvate and xylitol are the important bio-products and intermediates of microbial carbohydrate metabolism.
The major achievements of the group were:
1, Fuel ethanol production from lignocellulosic biomass:
Xylose reductase gene (XYL1), xylitol dehydrogenase gene (XYL2) and xylulose kinase gene (XKS1) from various yeasts were expressed in Saccharomyces cerevisiae. Also, bacterial transhydrogenase gene (udhA) from E. coli was cloned and expressed in the recombinant yeast.  The novel engineered strain could ferment xylose and regenerate NADPH simultaneously so that it could effectively ferment both glucose and xylose to produce ethanol under oxygen-limited condition.  The conversion yield of xylose to ethanol reacheed to 88%.  The Saccharomyces cerevisiae strain expressed pdc gene and vgb gene increased it’s ethanol production from from 6.8％ to 9.7％.
2, Construction of pyruvate hyper-producing strain
The pdc gene encoding pyruvate decarboxylase in Torulopsis glabrata was specifically disrupted. The disruptant displayed higher pyruvate accumulation and less ethanol production.  It accumulated 80 g/l of pyruvate in 100 L jar pilot fermentation under favorable conditions.
3, Xylitol production by biotechnology

The xylose reductase gene from Pichia stipitis was cloned and expressed in Saccharomyces cerevisiae.  The recombinant yeast could convert xylose to xylitol with the yield of 90 %.  In order to construct a novel strain which can ferment glucose to produce xylitol directly, the key enzyme D-arabitol dehydrogenase gene from Gluconobacter oxydans was cloned and functional expressed in Escherichia coli

Selected publications
Q-H Wang, P He, D-J Lu, AShen,Niang*:Metabolic Engineering of Torulopsis glabrata for ImprovedPyruvate roduction，Enzyme Microb. Technol.，36:832-839,2005
X-L Liu, N Jiang*, P He, D-J Lu, A Shen :Fermentation of xylose to produce ethanol by recombinant Saccharomyces cerevisiae strain containing XYLA and XKS1, Chinese Sci. Bull.,50:652-657,2005
H-R Cheng , N Jiang,* A Shen, Y-J Feng: Molecular cloning and functional expression of D-arabitol dehydrogenase gene from Gluconobacter oxydans in Escherichia coli, FEMS Microbiol Lett., 252:35-42, 2005
刘小琳、贺鹏、卢大军、沈安、江宁*：絮凝选择载体的构建及β－ 葡萄糖苷酶基因在酿酒酵母中的表达，生物工程学报，21(1)：167-170,2005.

Patent
Ning Jiang, Peng He, et. al., A xylitol production method and its specific strain 200510008756.1,

Laboratory Staff
An Shen  Associate Professor
Peng He  Assistant Professor
Shuhao Wang  Associate Professor
Dajun Lu  Research Associate

Students
Changying Guo, Hua Yan, 2002;
Changsheng Wu, Hairong Cheng, 2003;
Pingying Wei, 2004;
Zilong Li, Yuping Lan, 2005  

Guest Students
Yingmin Xue，China Agricultural University;
Changzheng Zhao, Beijing Normal University;
Yongbo Yuan, Beijing Science and Technology University.