Abstract Background Gamma-aminobutyric acid (GABA) is an important bio-product used in pharmaceuticals and functional foods as a precursor of the biodegradable plastic polyamide 4. Glutamate decarboxylase (GAD) converts l -glutamate ( -Glu) into GABA via decarboxylation. Compared with other methods, develop bioconversion platform to produce considerable interest for industrial use. Results Thre...