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Table 1 Bacterial strains that affect neurotransmitter and stress hormone production- an update from Clarke et al [21]

From: Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes

Molecule Probiotic Strain, microbial metabolite Species Effects
Tryptophan- precursor to 5-HT Bifidobacterium infantis Rats Aids in combating psychiatric disorders such as depression [84]
  Lactobacillus johnsonii In vitro model Reduces serum kynurenine concentrations and IDO activity in vitro in HT-29 colonic cells, which prevents the breakdown of tryptophan [138]
Serotonin Lactococcus lactis subsp. Cremoris (MG 1363), Lactococcus lactis subsp. Lactis (IL 1403), Lactobacillus plantarum (FI8595), Streptococcus thermophilus (NCFB2392), Eschericchia coli K-12, Morganella morganii (NCIMB, 10466), Klebisella pneumoniae (NCIMB, 673), Hafnia alvei (NCIMB, 11999) In vitro model Produce serotonin [47, 139]
  Butyrate and acetate produced by bacteria Mice Induce serotonin synthesis in a dose-dependent manner by regulating the gene Tph1 that synthesizes serotonin [68]
Dopamine Bacillus cereaus, Bacillus mycoides, Bacillus subtilis, Proteus vulgaris, Serratia marcescens, S. aureus, E.col, E.coli K-12, Morganella morganii (NCIMB, 10466), Klebisella pneumoniae (NCIMB, 673), Hafnia alvei (NCIMB, 11999) In vitro model Produce dopamine [140142]
GABA Lactobacillus rhamnosus (JB-1) Mice Regulates GABA receptor expression and reduced stress-induced corticosterone, anxiety and depression [143]
  Bifidobacterium dentium DPC6333, Bifidobacterium dentium NCFB2243, B. infantis UCC35624, Bifidobacterium adolescentis DPC6044, Lactobacillus brevis DPC6108, Bacillus mycoides, Bacillus subtiles, Proteus vulgaris, Lactobacillus rhamnosus YS9 Humans Lactobacillus brevis DPC6108 was the most effective at producing GABA [8].
Cortisol Lactobacillus helveticus R0052; Bacteroidetes longum R0175 Humans Reduce urinary free cortisol output [133, 144]
Noradrenaline B. mycoides, B. subtilis, P. vulgaris, S. marescens, E. coli K-12 In vitro chromatography Regulates motility and secretions in the ENS. Elevated levels due to acute stress can cause the growth of pathogenic E. coli [140].