ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Production of L-tryptophan by enantioselective hydrolysis of D,L-tryptophanamide using a newly isolated bacterium

Jian-Miao Xu, Ben Chen, Yuan-Shan Wang, and Yu-Guo Zheng

Institute of Bioengineering, Zhejiang University of Technology, 310014, Hangzhou, China

E-mail: zhengyg@zjut.edu.cn

Abstract: Bacterial strain ZJB-09211 capable of amidase production has recently been isolated from soil samples. The strain is able to asymmetrically hydrolyze L-tryptophanamide from D,L-tryptophanamide to produce L-tryptophan in high yield and with excellent stereoselectivity (enantiomeric excess > 99.9 %, and enantiomeric ratio > 200). Strain ZJB-09211 has been identified as Flavobacterium aquatile based on the cell morphology analysis, physiological tests, and the 16S rDNA sequence analysis. Optimization of the fermentation medium led to an about six-fold increase in the amidase activity of strain ZJB-09211, which reached 501.5 U L⁻¹. Substrate specifity and stereoselectivity investigations revealed that amidase of F. aquatile possessed a broad substrate spectrum and high enantioselectivity.

Keywords: l-tryptophan – Flavobacterium aquatile – amidase – enantioselective biocatalysis

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0389-6

Chemical Papers 67 (10) 1262–1270 (2013)