Table 1.
Microbiota-derived tryptophan metabolites and gut microbiota species.
| Microbial tryptophan metabolites | Enzymes | References | Producers | References | |
|---|---|---|---|---|---|
| Indole | Tryptophanase (TNA) | (28, 40) | Bacteroides ovatus | Enterococcus faecalis | (11, 76–80) |
| Clostridium limosum | Escheichia coli | ||||
| Clostridium bifermentans | Fusobacterium nucleatum | ||||
| Clostridium malenomenatum | Haemophilus influenza | ||||
| Clostridium lentoputrescens | Proteus vulgaris | ||||
| Clostridium tetani | Paracolobactrum coliforme | ||||
| Clostridium tetanomorphum | Pseudomonas. aeruginosa | ||||
| Clostridium sordellii | Peptostreptococcus asscharolyticus | ||||
| Clostridium ghoni | Salmonella enterica | ||||
| Corynebacterium acnes | Vibrio cholerae | ||||
| Citrobacter koser | …for more see (76, 81) | ||||
| Indole-3-acid-acetic (IAA) | Tryptophan decarboxylase (TrD) | (30) | Bacteroides thetaiotaomicron | Clostridium sporogenes | (69, 78, 82–85) |
| Bacteroides eggerthii | Clostridium perfringens | ||||
| Indole-3-acetaldehyde oxidase | Bacteroides ovatus | Clostridium putrefaciens | |||
| Bacteroides fragilis | Clostridium saccharolyticum | ||||
| Tryptophan 2-monooxygenase (TMO) | Bifidobacterium adolescentis | Clostridium sticklandii | |||
| Bifidobacterium longum subsp. longum | Clostridium subterminale | ||||
| Diamine oxidase | Bifidobacterium pseudolongum | Clostridium subterminale | |||
| Clostridium bartlettii | Escherichia coli | ||||
| Monoamine oxydase (MAO) | Clostridium difficile | Eubacterium hallii | |||
| Clostridium lituseburense | Eubacterium cylindroides | ||||
| Clostridium paraputrificum | … for more see (82) | ||||
| 3-methylindole (skatole) | Indoleacetate decarboxylase (IAD) | (30, 65) | Bacteroides thetaiotaomicron | Eubacterium cylindroides | (86, 87) |
| Butyrivibrio fibrisolvens | Eubacterium rectale | ||||
| Clostridium bartlettii | Megamonas hypermegale | ||||
| Clostridium scatologenes | Parabacteroides distasonis | ||||
| Clostridium drakei | … for more see (65, 88) | ||||
| Indole-3-acrylic acid (IA) | Aromatic amino acid aminotransferase (ArAT) | (11, 65) | Clostridium sporogenes | (12, 69, 89, 90) | |
| Phenyllactate dehydrogenase (fldH) | Peptostreptococcus russellii | ||||
| Phenyllactate dehydratase (fldBC) | Peptostreptococcus anaerobius | ||||
| Pyruvate: ferredoxin oxidoreductase B and C (porB, C) | Peptostreptococcus stomatis | ||||
| … for more see (91) | |||||
| Indole-3-propionic acid (IPA) | Acyl-CoA dehydrogenase (acdA) | (30) | Bacteroides | Escherichia. coli | (69, 89, 92, 93) |
| Clostridium botulinum | Peptostreptococcus asscharolyticus | ||||
| Clostridium caloritolerans | Peptostreptococcus russellii | ||||
| Clostridium paraputrificum | Peptostreptococcus anaerobius | ||||
| Clostridium sporogenes | Peptostreptococcus stomatis | ||||
| Clostridium cadvareris | … for more see (94) | ||||
| Indole-3-lactic acid (ILA) | Aromatic amino acid aminotransferase (ArAT) | (30, 65) | Anaerostipes hadrus | Clostridium sporogenes | (69, 83, 95–97) |
| Anaerostipes caccae | Clostridium saccharolyticum | ||||
| Bacteroides thetaiotaomicron | Escherichia coli | ||||
| Bacteroides eggerthii | Eubacterium rectale | ||||
| Bacteroides ovatus | Eubacterium cylindroides | ||||
| Phenyllactate dehydrogenase (fldH) | Bacteroides fragilis | Faecalibacterium prausnitzii | |||
| Bifidobacterium adolescentis | Lactobacillus murinus | ||||
| Bifidobacterium bifidum | Lactobacillus paracasei | ||||
| Bifidobacterium longum subsp. infantis | Lactobacillus reuteri | ||||
| Bifidobacterium longum subsp. longum | Megamonas hypermegale | ||||
| Pyruvate: ferredoxin oxidoreductase B and C (porB, C) | Bifidobacterium pseudolongum | Parabacteroides distasonis | |||
| Clostridium bartlettii | Peptostreptococcus asscharolyticus | ||||
| Clostridium perfringens | … for more see (40) | ||||
| Indole-3-aldehyde (IAld) | Tryptophanase (TNA) | (98) | Lactobacillus johnsonii | (96, 99, 100) | |
| Lactobacillus. reuteri | |||||
| Lactobacillus. acidophilus | |||||
| Lactobacillus. murinus | |||||
| …for more see (100) | |||||
| Tryptamine | Tryptophan decarboxylase (TrpD) | (98) | Bacteroides | (93, 101) | |
| Clostridium sporogenes | |||||
| Escherichia. coli | |||||
| Firmicutes C. sporogenes | |||||
| Ruminococcus gnavus | |||||
| …for more see (93) | |||||
| Indole-3-acetaldehyde (IAAld) | Diamine oxidase | (40) | Escherichia coli | (102) | |
Each indole derivative corresponds to the enzyme required for the process of synthesis of that derivative from tryptophan.