Production of γ-aminobutyric acid by Streptococcus salivarius subsp. thermophilus Y2 under submerged fermentation

Abstract

Gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the central nervous system, has several well-known physiological functions and has been applied to the production of many drugs and functional foods. The technology of GABA production via submerged fermentation by Streptococcus salivarius subsp. thermophilus Y2 was investigated in this paper. It indicated that the GABA production was related to the biochemical characteristics of glutamate decarboxylase (GAD) of S. salivarius subsp. thermophilus Y2. After 24 h of fermentation at 37 degrees C, which is the suitable culture conditions for GAD-production, then the culture condition were adjusted to the optimal temperature (40 degrees C) and pH (4.5) for the GAD reaction activity in biotransformation of cells and pyridoxal 5'-phosphate (0.02 mmol/l) were added to the broth at the 48 h, the GABA production was increased up to 1.76-fold, reaching 7984.75 +/- 293.33 mg/l. The strain shows great potential use as a starter for GABA-containing yoghurt, cheese and other functional fermented food productions.

Production of GABA (gamma amino butyric acid) by Lactic Acid Bacteria

“…paracasei NFRI 7415 isolated from Japanese traditional fermented food funasushi (Komatsuzaki et al, 2005). Recently, Yang et al (2008) has reported to produce 78 mM of GABA using Streptococcus salivarius in China, and domestic researchers are developing the isolation of strains producing GABA and have reported to produce 19 mM, 251 mM of GABA respectively by isolation of GABA-producing strains such as Lb. brevis OPK 3, Lb.…”

Enhancement of γ-Amminobutyric Acid Production by Co-Culturing of Two Lactobacilli Strains

“…However, S. salivarius subsp. thermophilus Y2 did not increase GABA production significantly when glutamate was added 10-20 g LG 1 of media, suggesting that these concentrations of glutamate are not appropriate for the synthesis of GABA in this species (Yang et al, 2008).…”

“…The contents of extracellular GABA accumulated in the culture medium were extracted according to the method of Yang et al (2008) with minor modifications. First, the culture broth was separated from cells by centrifugation (8000×g for 15 min at 4°C) and the supernatant was diluted 50 fold with 7% (v/v) of glacial acetic acid.…”

“…The biosynthesis of GABA in microorganisms is mainly regulated by pH, which usually has the most pronounced effect for a fermentation process (Yang et al, 2008). To investigate the effect of different pH levels on biomass and the production of GABA by L. brevis and L. plantarum, the initial pHs of the media were adjusted to 4, 5, 6, 7 and 8.…”

“…The GABA production appeared to correlate with the acidification of the medium, hence, it is probable that two strains collaborated in the production of GABA as a result of acid-resistant response. It was reported that GABA production can be effectively improved by maintaining cellular pH of the medium to acidic conditions because GAD must consume an H + ion for GABA production (Yang et al, 2008). In addition, pH-regulated genes encoding a GABA transporter was shown to have an acidic pH optimum and preferentially expressed at acidic ambient pH (Espeso and Arst, 2000).…”