Abstract:

A γ-aminobutyric acid (GABA)-producing strain X-1 was isolated from soil samples by paper chromatography.
Based on morphological characteristics, and 16S rDNA sequence and phylogenic analyses, X-1 was identified as Bacillus
megaterium. The culture medium of Bacillus megaterium X-1 was studied by single factor and orthogonal array designs.
The optimal medium components were 30.0 g/L glucose, 30.0 g/L peptone, 0.6 g/L K2HPO4, 0.3 g/L pyrodoxal-5-phosphate,
10.0 g/L monosodium glutamate, 3.0 g/L NaNO3, 0.5 g/L MgSO4·7H2O, and 0.01 g/L FeSO4·7H2O. Using the optimized medium,
the highest GABA yield of 21.57 mmol/L was obtained, representing a 4.83-fold increase over that before optimization.

Key words: γ-aminobutyric acid, screening, culture medium optimization