Gamma Amino Butyric Acid (GABA) and Ferulic Acid Esterase (FAE) Producing Psychobiotic Bacteria Isolated from Cereal‑Based Fermented Food.

Gut microbiota plays an important role in regulating enteric, immune and neural pathways. Many neuropsychiatric disorders
such as anxiety, depression, autism and cognitive behaviour are associated with gut dysbiosis. Gamma-aminobutyric acid
(GABA) and short-chain fatty acids produced by gut bacteria influence gastrointestinal and neurological functions. Ferulic
acid esterase (FAE) which releases ferulic acid (FA) from feruloylated sugar ester conjugates, naturally found in grains,
fruits and vegetables, is also produced by some gut bacteria and helps prevent neurodegeneration. These properties provide
bacteria with the ability to maintain intestinal barrier function and prevent neuropsychiatric disorders. Therefore, this study
aims to isolate GABA and FAE-producing LAB and characterize their bioactive and probiotic properties. A total of twelve
cultures were isolated, of which eight bacteria positive for GABA, FAE and SCFA production were selected for further
investigation. All selected bacteria were positive for bile salt hydrolase (BSH) and showed acid tolerance, resistance to bile
salt, stimulated gastric and pancreatic juice, and auto- and co-aggregation properties. Furthermore, selected LAB showed
mucin adhesion efficiency greater than 80% and exhibited γ-hemolytic activity. 16S rRNA sequencing identified NS0969,
B1, C1, C2, M1, M2, and R2 as Limosilactobacillus fermentum and R1 as Lactiplantibacillus pentosus. This study showed
that selected bacteria and/or their postbiotic preparations can be used as potential psychobiotics.