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

Abstract

Aim: To investigate the possibility of finding a new homocysteine (Hcy) γ‐lyase with the desired properties for Hcy measurement in bacteria. Methods and Results: Through a process of enrichment, the Hcy γ‐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 γ‐lyase was obtained when the isolate was cultured at 30°C at pH 6·5 for about 36 h in the optimum medium. Results also showed that this Hcy γ‐lyase has relatively high specificity towards Hcy. Conclusions: Because of its high specificity for Hcy, this bacterial Hcy γ‐lyase has the potential application in Hcy determination. Significance and Impact of the Study: In addition to isolating a bacterium that produces Hcy γ‐lyase suitable for Hcy determination, this study also indicates that the bacterium could be a source for production of Hcy γ‐lyase for clinical applications.

Characterization of Homocysteine γ-Lyase from Submerged and Solid Cultures of Aspergillus fumigatus ASH (JX006238)

“…The induction of A. fumigatus Hcy γ-lyase with homocysteine/methionine as substrates was consistent with previous results for Aspergillus SPRS-1a [38] and A. flavipes [21]. However, the preference of a yeast extract, rather than homocysteine, as a substrate for Hcy γ-lyase induction by Serratia N2-1 was also reported by Zhao et al [53]. Further experiments were conducted to assess the effect of various concentrations of the sulfur amino acids inducing the highest amounts of Hcy γ-lyase (L-methionine, homocysteine, and cysteine).…”

“…Therefore, Hcy γ-lyase with a unique specificity to homocysteine hydrolysis is the focus of this study. Hcy γ-lyase has already been purified and characterized from various bacterial species [17,26,48,53], yet only shown a slight specificity to dual action sulfur amino acids on homocysteine and methionine. Moreover, therapeutic enzymes of eukaryotic origin, in contrast to bacterial origin, have received much attention for their substrate specificity, as reviewed by El-Sayed [9].…”