Substrate sustained release-based high efficacy biosynthesis of GABA by Lactobacillus brevis NCL912

Abstract

BackgroundGamma-aminobutyric acid (GABA) plays a significant role in the food and drug industries. Our previous study established an efficient fed-batch fermentation process for Lactobacillus brevis NCL912 production of GABA from monosodium l-glutamate; however, monosodium l-glutamate may not be an ideal substrate, as it can result in the rapid increase of pH due to decarboxylation. Thus, in this study, l-glutamic acid was proposed as a substrate. To evaluate its potential, key components of the fermentation medium affecting GABA synthesis were re-screened and re-optimized to enhance GABA production from L. brevis NCL912.ResultsThe initial fermentation medium (pH 3.3) used for optimization was: 50 g/L glucose, 25 g/L yeast extract, 10 mg/L manganese sulfate (MnSO4·H2O), 2 g/L Tween-80, and 220 g/L l-glutamic acid. Glucose, a nitrogen source, magnesium, and Tween-80 had notable effects on GABA production from the l-glutamic acid-based process; other factors showed no or marginal effects. The optimized levels of the four key components in the fermentation medium were 25 g/L glucose, 25 g/L yeast extract FM408, 25 mg/L MnSO4·H2O, and 2 g/L Tween-80. A simple and efficient fermentation process for the bioconversion of GABA by L. brevis NCL912 was subsequently developed in a 10 L fermenter as follows: fermentation medium, 5 L; glutamic acid, 295 g/L; inoculum, 10% (v/v); incubation temperature, 32 °C; and agitation, 100 rpm. After 48 h of fermentation, the final GABA concentration increased up to 205.8 ± 8.0 g/L.Conclusionsl-Glutamic acid was superior to monosodium l-glutamate as a substrate in the bioproduction of GABA. Thus, a high efficacy bioprocess with 205 g/L GABA for L. brevis NCL912 was established. This strategy may provide an alternative for increasing the bioconversion of GABA.

Production of Gamma-Aminobutyric Acid from Lactic Acid Bacteria: A Systematic Review

“…Different strains of Lb. brevis produce GABA in the range from 15.0 mg/L to 205 g/L [17,18]. Similarly, different Lb.…”

“…Up to now, the highest yield of GABA by Lb. brevis is 205 g/L [18]. At the same time, various strains of one species have obvious differences in GABA productivity ( Supplementary Table S2).…”

A Brief Review on Glutamate Decarboxylase From Lactic Acid Bacteria

“…As mentioned above, a number of LAB carry two GAD-encoding genes, gadA and gadB. Frequently, studies have focused on the purification and characterization of GadB, e.g., from E. raffinosus [75], L. plantarum [79], L. brevis [78], L. sakei [80], L. paracasei [18] since the expression levels of recombinant GadB are typically higher than those for GadA [55]. A recent study by Wu et al showed that gadA transcript was highly upregulated (55-fold) in strain L. brevis NPS-QW-145 at the stationary phase of growth.…”

Environmental Conditions Affecting GABA Production in Lactococcus lactis NCDO 2118

“…Good amounts were obtained by growing Lactobacillus buchneri in corncob hydrolysate and xylose [ 14 ] or Lactobacillus rhamnosus in fermented adzuki bean milk [ 15 ]. Lactobacillus brevis strains isolated from quinoa sourdough [ 16 ] or kimchi [ 17 ] fermentation as well as L. brevis cultures fortified with divalent cations (Mg 2+ ) and tween-80 [ 18 ] also display promising GABA yields. Co-cultures of Corynebacterium glutamicum and Lactobacillus plantarum [ 18 ], as well as entrapped [ 19 ] or immobilized [ 20 ] L. brevis cells were also described together with immobilized GAD enzyme [ 21 ] as a means to obtain economically sustainable GABA production.…”