Optimization of Gamma Aminobutyric Acid Production from Various Protein Hydrolysates by Lactiplantibacillus plantarum MCM4

Abstract

Background and Objective: Gamma aminobutyric acid (GABA) is a non-protein amino acid with various physiological properties that is used as synthetic drugs for curing anxiety, acute stress, and hypertension. In the recent years, producing the GABA-enriched foods and supplements via biological methods has gained much attention. Material and Methods: In this study, at first, one factor at a time (OFAT) approach was used to study the effect of various kinds of protein hydrolysates (soy protein isolate (SPI), whey protein concentration (WPC) and casein) at different concentrations, fermentation time (24 to 72h) and inoculum size (1, 3, and 5% v/v) on GABA synthesis. Then, the most effective parameters i.e., soy protein hydrolysate (SPH) concentration, inoculum size, and fermentation time were further employed by central composite design (CCD)-based response surface methodology (RSM) for GABA synthesis by Lactobacillus plantarum MCM4. Results and Conclusion: Among different protein hydrolysates, SPH was found to be more suitable for GABA synthesis. Moreover, higher GABA content was obtained when soy protein with extended enzymatic hydrolysis (SPH6) was used as the substrate. The polynomial mathematic model could predict the GABA synthesis successfully. The optimization using CCD indicated that the maximum GABA syntehsis yield (19.387 mg GABA/100 mL) was achieved under optimium conditions (fermentaion time of 28.99 h, inoculum size of 3.65% v/v, and SPH6 concnetration of 3.89% w/v). Overall, L. plantarum MCM4 was found to be a novel LAB species to produce GABA from inexpensive sources.

Keywords

• fermentation, lactic acid bacteria, gamma aminobutyric acid (gaba), protein hydrolysate