Production of γ-aminobutyric acid during fermentation of Gastrodia elata Bl. by co-culture of Lactobacillus brevis GABA 100 with Bifidobacterium bifidum BGN4

Gastrodia elata Bl. (GE) is a traditional herbal medicine used for the prevention of cerebrovascular disease and for the regulation of one's blood pressure. gamma-Aminobutyric acid (GABA) is known to be beneficial for preventing neurological disorders and hypertension. The objective of this study was to develop fermented GE products containing high levels of GABA. The optimal medium conditions for the production of GABA during fermentation were as follows: an initial pH of 6.5, 3% (w/v) l-monosodium glutamate, 10% (w/v) freeze-dried GE powder, and 0.5% (w/v) yeast extract. The production of GABA was further enhanced by the co-culture of Lactobacillus brevis GABA 100 with Bifidobacterium bifidum BGN4. During fermentation, high amounts of organic acids and GABA were produced, while gastrodin, the main polyphenol compound of GE, was completely converted to 4-hydroxybenzylalcohol. The fermented GE product with GABA was successfully produced by optimizing the fermentation conditions.