Optimal Reaction Conditions for the Production of γ-Aminobutyric Acid by the Marine Yeast Isolate Pichia anomala MR-1 Strain

The optimal conditions for the production of gamma-aminobutyric acid (GABA) by the marine yeast isolate Pichia anomala MR-1 strain appeared to be completely different from those required for growth and biomass production of the yeast strain. By proper reaction temperatures and pH levels, the efficiency of GABA production was improved dramatically. Supplying enough energy for the reaction was another important technical element to improve the production efficiency of GABA. The MR-1 isolate was found to use various saccharides, including glucose and fructose, as well as intermediate metabolites in the tricarboxylic acid (TCA) cycle to promote GABA production. On the other hand, ethanol, various free amino acids, and organic acids were detected along with GABA in the reaction solution. These results suggest that production of GABA by the MR-1 strain is not due to a single enzymatic reaction. Rather it is a fermentation reaction, possibly involving a combination of intracellular metabolic pathways.