High production of GABA by fermentation is not only
dependent on activating the activities of GAD but also on
inhibiting the activities of GABA-decomposing enzymes. One
pathway for GABA decomposition exists in a large variety of
plants and microorganisms. GABA transaminase catalyses the reversible conversion of GABA to succinic semi-aldehyde
using either pyruvate or α-ketoglutarate as the amino acceptor,
and succinic semi-aldehyde dehydrogenase catalyzes the
reversible conversion of succinic semi-aldehyde to succinate