gamma amino butyric acid (gaba) is an important bioactive compound in pharmaceutical fields, gaba is found at high concentrations in the brain and plays a fundamental role in inhibitory neurotransmission in several of its routes within the central nervous system, and also in peripheral tissues. the strategy of biological production of gaba has been based on the efficient conversion of glutamate into gaba by glutamic acid decarboxylase (gad). here, we focused on the lactic acid bacteria (lab) as gaba and gad producers, because lab have a high potential commercially as the starters for functional fermented food production. in addition, some lab have been considered as probiotics, whose products have been of interest in the nutraceutical fields. it is basic technique to culture gaba-producing bacteria in the optimal medium where lab can growth actively in order to produce gaba.the composition of medium for gaba production would not differ significantly from the medium for growth of lab.glucose, maltose and sucrose as carbon source were selected, and yeast extract, soybean and small amount of metal ions as nitrogen source showed to be suitable. in general, the fermentation conditions for the growth of lactic acid bacteria have been equally applicable to the production of gaba.the substrate specificity of gad from lab was tested by using 22 kinds of amino acid.the decarboxylated product was observed only for l-glutamic acid. these results indicate that gads from lab are specific for l-glutamic acid.

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