Regulation of the Gut Microbiota and Serum Neurotransmitters by Streptococcus thermophilus GA8- and Lacticaseibacillus rhamnosus HAO9-Fermented Milk Containing High Levels of Gamma-Aminobutyric Acid

Gamma-aminobutyric acid (GABA) is an important neurotransmitter in the human body, with several negative emotions reported as being associated with GABA dysregulation. Probiotic microorganisms, such as Lactobacillus spp., Lactococcus spp., and Streptococcus thermophilus, have been used to develop GABA-rich probiotic supplements and fermented foods.