The Production of γ-Aminobutyric Acid from Free and Immobilized Cells of Levilactobacillus brevis Cultivated in Anaerobic and Aerobic Conditions

Abstract

γ-aminobutyric acid (GABA) has several beneficial effects on human health. GABA may be produced via chemical synthesis or through microbial metabolism, and Levilactobacillus brevis is recognized as a GABA-producing species. In this study, 11 Lvb. brevis strains were screened for GABA production, and the best producers were selected to verify the effect of aerobic (AE) and respiratory (RS) cultivations on growth parameters, biomass, and GABA accumulation. Lvb. brevis LB12 was then used to evaluate the combined effect of the incubation atmosphere (anaerobiosis vs. aerobiosis), cell protection (free vs. immobilized cells), and cell recycling (fresh vs. starved cells) on GABA production. Glutamate (GLU) consumption and GABA accumulation were detected by Thin-layer Chromatography (TLC) and RP-HPLC analyses. The ability to produce GABA was widespread among the strains. AE and RS growth improved biomass production, but oxygen availability impaired GLU to GABA conversion, and the anaerobically growing cells had the highest GABA productivity. Immobilized strains had lower efficiency in both GLU uptake and conversion compared to free cells, probably due to the poor diffusion in alginate beads. The use of resting cells allowed further GABA production without the cultivation step, but cell activity was exhausted after three cycles of reutilization. Lvb. brevis LB12 is an excellent GABA producer, and AE cultivation can be exploited to improve the final cell density; however, the conditions for boosting GLU to GABA conversion and cell regeneration need to be further investigated.

Inhibition of blood pressure elevation in GABA‐enriched Hidakakombu fermented with Lactiplantibacillus plantarum 002 protected addition of trehalose

“…In contrast, immobilisation significantly reduced GABA content. A reduction in GABA productivity has been demonstrated during the immobilisation of Levilactobacillus brevis , owing to the lower efficiency of glutamate conversion (Zotta et al ., 2022). In this study, the GAD of L. plantarum 002 was also reduced by the formation of an outer membrane by Ca‐alginate, which may have prevented the GAD of L. plantarum 002 from being expelled from L. plantarum 002 thereby reducing the GABA content.…”

Microbial-Derived γ-Aminobutyric Acid: Synthesis, Purification, Physiological Function, and Applications

“…105 Zotta et al used the PITC-derived method to screen Levilactobacillus brevis with high GABA-producing properties and verified the effects of aerobic and respiratory cultivations on various growth parameters, biomass production, and GABA accumulation. 106 In addition, OPA has also been used as a derivatization reagent to analyze the amount of GABA in plant foods and medicinal plants. 12 Therefore, it becomes possible to accurately quantify the GABA content in fermentation broth by utilizing HPLC and appropriate derivatization techniques.…”

“…Wu et al screened high GABA-producing LAB strains isolated from Korean kimchi by the dansyl chloride derivation method, and a total of 9 LAB isolates were confirmed as high GABA producers by RP-HPLC . Zotta et al used the PITC-derived method to screen Levilactobacillus brevis with high GABA-producing properties and verified the effects of aerobic and respiratory cultivations on various growth parameters, biomass production, and GABA accumulation . In addition, OPA has also been used as a derivatization reagent to analyze the amount of GABA in plant foods and medicinal plants .…”

Biosynthesis of Gamma-Aminobutyric Acid by Engineered Clostridium tyrobutyricum Co-Overexpressing Glutamate Decarboxylase and Class I Heat Shock Protein

“…Cell number is a key factor responsible for GABA production [9]; however, anaerobic conditions interfere with the bacterial growth of these traditional aerobic GABA producers, creating obstacles to obtaining a large cell count. Currently, several attempts have been made to carry out the synthesis of GABA under anaerobic conditions, such as using Levilactobacillus brevis, Lactobacillus brevis, Bifidobacterium adolescentis, and Bifidobacterium dentium, but their GABA production (4.94-43.99 g/L) was unsatisfactory [19,24,25]. Clostridium tyrobutyricum is an anaerobic, Gram-positive, spore-forming, and non-pathogenic bacterium mainly used for short-chain fatty-acid production [26].…”