Isolation of a homocysteine γ-lyase-producing bacterium and study of its enzyme production conditions

Abstract

To investigate the possibility of finding a new homocysteine (Hcy) gamma-lyase with the desired properties for Hcy measurement in bacteria. Through a process of enrichment, the Hcy gamma-lyase-producing bacterium strain N2-1 was isolated from soil. Based upon its morphological, physiological, and biochemical characteristics, as well as its 16S rDNA sequence and phylogenetic tree analysis, this isolate belongs to the genus Serratia. The effects of pH, aeration, inducers, carbon (C) and nitrogen (N) sources on enzyme production were studied. Methionine, yeast extract, and glucose were selected as the optimal inducer, C and N sources, respectively. Maximum production of Hcy gamma-lyase was obtained when the isolate was cultured at 30 degrees C at pH 6.5 for about 36 h in the optimum medium. Results also showed that this Hcy gamma-lyase has relatively high specificity towards Hcy. Because of its high specificity for Hcy, this bacterial Hcy gamma-lyase has the potential application in Hcy determination. In addition to isolating a bacterium that produces Hcy gamma-lyase suitable for Hcy determination, this study also indicates that the bacterium could be a source for production of Hcy gamma-lyase for clinical applications.