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.

Plant-Based Nutraceutical Formulation Modulates the Human Gut Microbiota and Ferulic Acid Esterase Activity During In Vitro Fermentation.

Oxidative stress is an imbalance between free reactive oxygen species and antioxidant defences leading to neurological and other chronic disorders. The interaction between food and gut microbiota and their metabolites significantly reduces oxidative stress and influences host physiology and metabolism. This process mainly involves enzymes that hydrolyse complex polysaccharides and produce metabolites. Ferulic acid esterases (FAE) one of the most important enzymes of the gut microbiome, release ferulic acid from feruloylated sugar ester conjugates, that occur naturally in grains, fruits, and vegetables. FA is crucial in combating oxidative stress resulted from free radical formation. This study investigated the effect of two plant-based nutraceutical formulations, cereal-millet-based (PC1) and fruit-vegetable-based (PC2), on gut microbiota and the production of FAE, short chain fatty acids (SCFA) and other small metabolites in in vitro fermentation using human faecal samples. After in vitro fermentation, both nutraceutical formulations increased the abundance of Bifidobacterium, Lactobacillus, Prevotella, Feacalibacteria, and Clostridium leptum. Furthermore, they induced the production of FAE, xylanase and pectinase enzymes, SCFA and other small metabolites, resulting in increased antioxidation activity of the fermentate. PC1 stimulated FAE and xylanase production more effectively. These results demonstrated a positive correlation between the feruloylated nutraceutical formulation and the production of FAE and other accessory enzymes, suggesting that PC1 and PC2 stimulate the proliferation of the FAE-producing microbial consortium of the gut microbiome and therefore, increase FA and SCFA concentration. From this study it is evident that FA-rich plant-based formulation can be used as a prophylactic nutraceutical supplement to alleviate oxidative stress by modulating the gut microbiota.

Prophylactic effect of pectic oligosaccharides against poly I: C- induced virus-like infection in BALB/c mice.

Pectin oligosaccharides (POS) are pectin-derived prebiotics that exerts anti-inflammatory effects on the host and stimulates an innate immune response. The role of POS in protective immunity against viral infections is not very obvious. Therefore, the prophylactic effect of POS in the mouse model induced by Poly I: C mimicking viral infection was examined. Mice fed POS showed a significant (p ≤ .05) increase in IgG, sIgA, IgA, IL-12, and a significant (p ≤ .05) decrease in the concentration of pro-inflammatory cytokines IL-5, IL-6, IL-13 and IL-17 in lung and blood serum after Poly I: C stimulation. However, the control group could not inhibit pro-inflammatory cytokines. POS also promoted the growth of the Lactobacillus, Prevotella, Rilenellaceae, and Lachanospiraceae groups. Therefore, this study demonstrate that POS has the potiential to protect against viral inflammation by altering gut microbiota and activating mucosal immunity. PRACTICAL APPLICATIONS: POS is 2-10 mer oligomers of pectin. The human gastrointestinal tract lacks the enzyme to break down POS. They are fermented by gut bacteria in the colon and stimulate the proliferation of specific gut bacteria that are positively correlated with the production of anti-inflammatory cytokines and SCFA. POS also stimulates the secretion of IgA, which inhibits bacterial and viral adhesion and protects the host. Therefore, POS can be used as a functional food ingredient in food to stimulate a specific group of gut bacteria and enhance preventive immunity.