Gut production of GABA by a probiotic formula: an in vitro study.

The objective of this study was to evaluate the influence of a probiotic formula on the production of neuroactive compounds in different parts of the colon in batch culture and in vitro gut simulator experiments. Thirteen lactic acid bacterial strains, belonging to the species Levilactobacillus brevis, Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, Ligilactobacillus salivarius, Streptococcus thermophilus, were characterised for their in vitro ability to produce neurotransmitters. L. brevis P30021 and L. plantarum P30025 were selected based on their capability to produce γ-aminobutyric acid (GABA) and acetylcholine in vitro. A probiotic formulation with potential psychobiotic activity was prepared and tested in a batch culture of human microbiota monitoring the formation of GABA and acetylcholine. Samples of the three colonic tracts were taken from the Simulator of the Human Intestinal Microbiota (SHIME®) evaluating the production of GABA and other neurotransmitters by LC-MS. Short chain fatty acids (SCFA) by GC and microbiota composition by 16S rRNA gene sequencing were also determined. Probiotic supplementation led to the formation of GABA and acetylcholine with a decrease in glutamate concentrations in the in vitro batch fermentation. Production of GABA after the treatment with probiotics was confirmed in the SHIME® short-term experiment. No differences in short-chain fatty acids were observed up to 72 h of fermentation. Different microbiota composition was found in the three different parts of the colon, with a higher abundance of Veillonellaceae in the ascending colon vessels. The probiotic-exposed microbiota showed higher levels of Bacteroides, a gut microbe associated with anti-inflammatory activities and a potential GABA producer. Results demonstrate the impact of the tested probiotic formula on gut microbiota structure and GABA production. In conclusion, the probiotic treatment changed the microbiota composition and increased neuroactive metabolites production, indicating promising potential as psychobiotics, even if further clinical evidence is needed to confirm the effectiveness of these probiotics in improving mental health.

Influence of different processing method on lignan content of selected Malaysian plant-based foods.

This research assessed the influence of pickling, fermentation, germination, and tea brewing on lignan content of a variety of food highly consumed in Malaysia. Lignans have been measured by a validated LC-MS/MS method. Secoisolariciresinol (SECO) was the most abundant compound in fermented and germinated samples. Pickling significantly decreased larisiresinol content by approximately 86 %. Fermentation increased lignan content in a mixture of flaxseed and mung beans (799.9 ± 67.4 mg/100 g DW) compared to the unfermented counterpart (501.4 ± 134.6 mg/100 g DW), whereas the fermentation of soybeans and mung beans did not significantly affect the SECO content. Germination increased lignan content, which reached its peak on day 6 of germination for all the tested matrixes. In tea brew, lignans concentration increased with brewing time reaching its highest concentration at 10 min of brewing. The results of this study expand the knowledge on the effect of processing on lignan content in food.