Pilot-scale production of D-p-hydroxyphenylglycine from DL-5-p-hydroxyphenylhydantoin by Burkholderia cepacia JS-02

Abstract

In a 50L pilot scale reactor D-p-hydroxyphenylglycine (D-HPG) is produced enzymatically from DL-5-p-hydroxyphenylhydantoin (DL-HPH) with the resting cells of Burkholderia cepacia JS-02, requiring only corn steep liquor as a nitrogen source instead of the expensive yeast extract or peptone required by other strains. Both the fermentation process for preparing resting cells and the bioconversion were optimized in 5 L bench scale reactors. The cells showed the highest hydantoinase and carbarnoylase activities (0.640 and 0.304 U/mL-borth, respectively) at a fermentation of 18 h when Co2+ ions and DL-5-methylthioethyl hydantoin as an inducer were used. The optimal temperature and initial pH for bioconversion were 40 degrees C and 9, respectively. However, starting from the initial pH 9, pH dropped rapidly to near 7, at which level both key enzymes showed considerable activity. A pilot-scale bioconversion was carried out in a 50 L reactor with a productivity of 0.68 g/L h. Unlike conventional processes, this process using B. cepacia JS-02 can utilize inexpensive nitrogen and carbon sources for the production of the resting cells that contain the key enzymes. Also, it showed a high specific productivity during bioconversion without the use of a buffer solution. An economic analysis of this process showed that these advantages could lower production costs effectively. (c) 2007 Published by Elsevier Inc.