Institute of Microbiology
Chinese Academy of Sciences
Tel: 86-10-64807415
E-mail: dingjy@sun.im.ac.cn

Education
B.S, Peking University, 1979-1982

Research Area
His group focuses on fundamental and applied aspects of industrial microbiology, especially in amino acid production. Research works include investigation on the mechanism of mutation of amino acid-producing mutants, strain improvement by genetic engineering and metabolic engineering, and investigation on the metabolic pathway of cyclic imide in microorganisms.

Current Research
Anuual demand for amino acids used in feed additives and pharmaceutical products is huge. Most of amino acids are currently manufactured in China. But the industrial production process has not been set up for a few limited kinds of amino acids such as L-tryptophan..
A microorganism with amino acidracemase activity was screend and identified as  Pseudomonas putida. The amino acid racemase has low substrate specificity. It has activity toward most aliphatic amino acids, but acromatic amino acids. A technique of L-tryptophan production was established by coupling the reactions catalyzed by amino acid racemase and    tryptophan synthase.In addition, two distinct amino acid racemase genes  from   Research associate P. putida were cloned. Only alanine racemase activity was found in recombinan  E. coli TG1 containing  DadX  gene. Another amino acid racemase encoded by alr gene showed low substrate specificity.  

Coryneform bacteria has played a principle role in the progress of amino acid fermentation industry. There is an urgent need for strain improvement by genetic engineering and metabolic engineering. Aspartokinase (AK) gene, phosphenol－pyruvate carboxylase (PPC)  gene and pyruvate carboxylase）PYC) genefrom wild type C. crenatum and AEC-resistant mutant strain were cloned and sequenced. Over expressions of those three genes in C.crenatum  were investigated. The simultaneous amplification of the activities of both   AKfbr  and PYC resulted in growth further increased and yielded about 50%  increase of L-lysine production in the middle phase and 18% increase in the late  phase. N-acetylglutamate kinase genes from wild typestrain of C.crenatum and L-arginine-producing mutant was cloned and sequenced. The accumulation of L-arginine of the mutant was resulted from the increase of the enzyme activity. Overexpression of argB yieded about 25% increase of L-arginine production

Selected publications
Zhao Zhi , Liu Yangjian, Wang Yu,  Zhang Yingzi, Ding Jiuyuan  Expression of Feedback- resistant Aspartate Kinase Gene in Corynebacterium crenatum  Acta  Microbioloica Sinica 2005 45(4):530-533.

Laboratory Staff
Yu Wang        Research associate
Yingzi Zhang  Research associate
Hanbai Zhou  Research associate
Zhi Zhao        Research assistant

Students
XiaofangChen       2003-2006
Kai Li                     2003-2006
ChunhuaZhang     2004-2007
Guiming Liu           2005-2008