Lactobacillus brevis FEM 1874 for the development of GABA-enriched cheese

Probiotic microorganisms have recently been shown to impact on brain development and function through the gut:brain axis. Lactobacillus brevis FEM1874 isolated from Traditional Mountain cheese has been reported produce high concentrations of gamma-aminobutyric acid (GABA) and to possesses Bile Salt Hydrolysis activity in vitro. GABA is synthesized from glutamate which is the most common amino acid in cheese. The aim of this study was to test the ability of the strain to convert glutamate to GABA during cheese production. Twenty experimental micro-cheeses were produced using a commercial starter strain (107 CFU/mL) and FEM1874 as adjunct culture. Four different concentrations (102, 103, 104, 105 CFU/mL) of FEM1874 were tested in quadruplicate. In order to follow the microbial evolution, samples of milk, curd and cheese after 20 days of ripening were enumerated in selective media. The control and experimental samples showed a similar trend, suggesting that both milk-resident and starter strains grew during ripening. However, the load of mesophilic lactobacilli in all experimental curd samples was higher than the control. The concentration of GABA and glutamic acid in cheese samples after 20 days of ripening was quantified by UHPLC-HQOMS. The amino acidic profiles showed that while the concentration of Lb. brevis FEM1874 in milk increased, the amount of both glutamic acid (from 284±97 to 202±44) and GABA (from 154±48 to 83±28) significantly decreased during cheese production. These results suggested that the experimental strain converted the glutamic acid to GABA, but that GABA may have subsequently been converted to succinate by GABA transaminases.