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Biotechnology and Applied Biochemistry (2002) 35, (107–113) (Printed in Great Britain)

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Immobilization of an L-aminoacylase-producing strain of Aspergillus oryzae into gelatin pellets and its application in the resolution of D,L-methionine

Ying-jin Yuan¹, Shu-hao Wang, Zheng-xiao Song and Rui-chang Gao

Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China

Key words: amino acid, enzymic resolution, immobilized pellet, orthogonal design.

¹To whom correspondence should be addressed (e-mail yjyuan@public.tpt.tj.cn).

The conditions for immobilization of an L-aminoacylase-producing strain of Aspergillus oryzae in gelatin and the enzymic characteristics of the immobilized pellets were studied. The optimal concentrations of gelatin, glutaraldehyde and ethyldiamine and time of immobilization were determined. Scanning electron micrographs reveal the cross-linked structure differences between the native and immobilized pellets. Optimum pH and temperature of the native and immobilized pellets were determined. Effects of ionic strength and substrate concentration on relative activity of the native and immobilized pellets were investigated in detail. The immobilized pellets were more stable over broader temperature and pH ranges. In addition, the immobilized pellets showed stable activity under operational and storage conditions. The immobilized pellets lost about 20% of their initial activity after five cycles of reuse. The results reported in this paper show the potential for using the immobilized A. oryzae pellets to resolve D,L-methionine.

Received 29 May 2001/10 December 2001; accepted 11 January 2002

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