Abstract:

A glutamate decarboxylase (GAD)-producing lactic acid bacteria (LAB) strain HS2 was isolated from pickled vegetable. When the biotransformation was conducted in cells with strain HS2 for 1 h, the content of γ-aminobutyric acid in biotransformation solution of strain HS2 was (13.114 ± 0.133) g/L. Base on morphological, physiological and biochemical characteristics, 16S rDNA and phylogenic analysis, the strain HS2 was identified as Pediococcus pentosaceus. The optimal temperature and pH for GAD activity were 35 ℃ and 4.5. The GAD from strain HS2 was stable at 50 ℃ for 4 h and resistant to pH in the range of 4.0－6.5. In addition, calcium ions could result in a significant increase of GAD activity, which resulted in an enhancement of GAD activity by 37.21% and 23.02% at the concentrations of 5 mmol/L and 50 mmol/L Ca2+. Similarly, Mg2+ and Mn2+ also could increase GAD activity at the concentration of 50 mmol/L, whereas Co2+ could improve GAD activity at the concentration of 5 mmol/L.

Key words: glutamate decarboxylase, Pediococcus pentosaceus, γ&ndash, aminobutyric acid, strain identification