Gamma-aminobutyric acid (GABA) is a four-carbon nonproteinogenic amino acid that considered a potent bioactive compound with numerous biological functions. This compound is synthesized by the action of glutamate decarboxylase (GAD) and widely present in prokaryotic and eukaryotic organisms.

Some bacteria release GABA to resist acid stress. Shewanella violacea is a marine bacteria which known to be able to survive under acidic pH condition. Even though these species own gad in their genome, its ability to produce GABA remains unknown. In this study, the production of GABA by S. violacea was observed.

S. violacea cells were grown under normal and acidic pH prior to GABA content measurement by an amino acid analyzer. The extracellular of S. violacea culture was harvested after 3 and 72h incubation and used as amino acid analysis samples.

Amino acid analysis of the extracellular of S. violacea culture shown that GABA was not detected in both pH culture conditions. Even though the incubation time was prolonged, GABA content remains not detected.

Based on this result, we can conclude that S. violacea may need other enhancers to produce GABA. Therefore, further manipulation of various substrate addition may be needed near the future to find the factor that enhances the production of GABA in S. violacea.