Probiotic potential of a BSH positive, high GABA producing strain, Lactobacillus brevis FEM 1874, isolated from traditional “wild” Alpine cheese

Probiotics appear to play a role in brain development and function through the gut: brain axis. Gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter, also works in the periphery through immuno-modulation and regulating adipocyte function. Importantly, GABA is produced in high amounts be certain lactobacilli. In Lactobacillus brevis ATCC 367, GABA production depends on the activity of two genes gadA and gadB, as well the presence of an antiporter gadC. gadA and gadC are expressed as an operon, whereas gadR represents a transcriptional regulator. We isolated Lactobacillus brevis FEM 1874 from a traditional “wild” fermented Alpine cheese and studied its putative probiotic traits. This novel strain is bile salt hydrolase (BSH) positive, carries gad genes and is able to produce high levels of GABA in pure culture compared to over 100 other local cheese isolates. We studied GABA production under different conditions by modifying pH and L-glutamate concentrations, as well as assessing the strains survival and ability to produce GABA within the human gut microbiota using anaerobic, pH controlled faecal batch cultures. L. brevis FEM 1874 growth on different prebiotic substrates was also measured as was its ability to survive upper gut acid and bile challenge. L. brevis FEM 1874 appears to be a strain with promising probiotic traits and may prove an important adjuvant in production of functional dairy products. However, further investigations are needed to assess whether this strain produces GABA within the gastrointestinal tract and how this may impact on host immune system and possibly brain function