Screening for gamma-aminobutyric acid (GABA) - producing lactic acid bacteria (LAB) isolated from Vietnnam sources

Abstract

Gamma-aminobutyric acid is a brain’s major inhibitory neurotransmitter in the central nervous system (CNS), with a variety of physiological functions. Lactic acid bacteria, being generally regarded as safe, play a vital role in the biosynthesis of γ -aminobutyric acid (GABA) in the presence of glutamic acid – a major substrate for the process. Therefore, using lactic acid bacteria as sources for gammaaminobutyric acid production is a natural and potential method for making full use of GABA and LAB. In the present study, LAB (Lactobacillus fermentum, Lactobacillus salivarus, Lactobacillus acidophilus, Lactobacillus rhamnosus) were isolated from various sources in Vietnam and screened for strains with highefficiency GABA formation. The optimal culturing time was determined by cultivating LAB in MRS broth containing 25 mg/ml MSG, at pH of 6.5 and 37ºC, for 24, 48, and 72 h of incubation. After extraction and thin layer chromatography (TLC) analysis, results indicated that four strains had GABA-formation ability and reached the highest GABA concentration after 72 h. After high performance liquid chromatography (HPLC) analysis, among four strains of interest, Lactobacillus fermentum showed the highest GABA (1.34 mg/g extract), suggesting that L. fermentum was found to be a promising GABA producer for food and pharmaceutical field. Keywords: Gamma-aminobutyric acid (GABA), Glutamate, Lactobacillus fermentum, Lactobacillus salivarus, Lactobacillus acidophilus, Lactobacillus rhamnosus, optimization, incubation time.