Page 33 - JCBP-3-3

Journal of Clinical and
Basic Psychosomatics Microbiota in psychosomatic disorders

Table 1. Summary of commensal bacteria, their key metabolites, function, and dysregulation
Bacteria Metabolites Metabolite function Dysbiosis
Lactobacillus spp. Lactic acid Lowers pH, inhibits pathogenic bacteria, and • High‑fat, low‑fiber, or high‑sugar diets favor
maintains gut barrier integrity. 21,22,46 pathogenic bacteria.
Acetic acid Provides antimicrobial effects, supports energy • Lack of dietary fibers and polyphenols limits
metabolism for colonocytes, and promotes Lactobacillus growth.
short-chain fatty acids (SCFAs) production. 21,22,46 • High levels of reactive oxygen species (ROS)
can damage Lactobacillus populations.
Exopolysaccharides Support gut lining and enhance immune modulation. 92 • Lactobacillus is sensitive to antibiotics, which
Bacteriocins Antimicrobial peptides that inhibit competing can disrupt its population.
pathogens. 71,72 • Bacteria, such as Clostridium difficile and
Escherichia coli can outcompete Lactobacillus
SCFAs Although Lactobacillus primarily produces lactic in dysbiosis.
acid, it can indirectly contribute to SCFA production • High levels of ROS can damage Lactobacillus
through interactions with other gut microbes. 10,27
populations.
Amino acid metabolites Influence host immune response and
(e.g., tryptophan metabolites) neurotransmitter production. 57,71,72
Bifidobacterium Lactic acid Lowers gut pH, inhibiting pathogens and supporting • Bifidobacteria thrive on dietary fibers
spp. gut barrier integrity. 27 (e.g., oligosaccharides), and low-fiber diets
Acetic acid Antimicrobial, energy source for colonocytes, and reduce their abundance.
promotes SCFA production. 27 • High‑fat, high‑sugar diets, and
pro-inflammation conditions favor pathogenic
SCFAs Acetate and formate support butyrate production by bacteria while inhibiting Bifidobacterium
cross-feeding other microbes and are also involved in growth.
energy metabolism and microbial interactions. 10,27,92,112 • Loss of acetate and lactic acid weakens
Tryptophan-derived indole Influence immune and neurological functions. 30,71,72 competitive advantage against pathogens.
compounds
Conjugated linoleic acid Anti-inflammatory and metabolic benefits. 21,22,46
B-group vitamins (e.g., B1, Important for host metabolism. 21,22,46
B2, B6, B9, B12)
Escherichia coli Acetate A SCFA that supports microbial interactions but can • Reduction in Lactobacillus and
also fuel pathogenic bacteria. 21,22 Bifidobacterium removes competition,
Ethanol & lactate Produced under anaerobic conditions, influencing allowing E. coli to expand.
microbial metabolism. 46 • E. coli thrives in inflamed environments where
LPS and oxidative stress are high.
Succinate A key intermediate in metabolism but can promote • High‑fat, high‑protein, and low‑fiber diets
inflammation when overproduced. 21,22 promote E. coli growth.
Indole & tryptophan Can have both beneficial and harmful effects • Some E. coli strains are highly resistant to
metabolites depending on the balance in the gut. 49,52 antibiotics, allowing them to dominate after
antibiotic use.
Vitamin K2 (Menaquinone) Beneficial for host blood clotting and bone health. 21,22,46
• In conditions like irritable bowel syndrome or
Lipopolysaccharides (LPS) A pro-inflammatory endotoxin found in E. coli’s outer inflammatory bowel disease (IBD), E. coli can
membrane that can trigger immune responses. 90 become more prevalent. 90
Enterotoxins (pathogenic Some E. coli strains, like enterotoxigenic E. coli,
strains only) produce toxins that cause diarrhea.
Faecalibacterium Butyrate A SCFA that strengthens the gut barrier by fueling • F. prausnitzii thrives on fermentable fibers
prausnitzii colonocytes. 89 (prebiotics), and a fiber-deficient diet leads to
It also reduces inflammation by promoting its decline.
anti-inflammatory cytokines (e.g., interleukin-10). 141 • Conditions, such as IBD and metabolic
Lowers gut pH, inhibiting pathogenic bacteria. 10 disorders create an unfavorable environment
Propionate Another SCFA involved in lipid metabolism and for F. prausnitzii.
immune modulation. 130 • Antibiotic use: broad‑spectrum antibiotics
significantly reduce F. prausnitzii levels.
Acetate Serves as a precursor for butyrate production by • F. prausnitzii is highly sensitive to oxidative
cross-feeding other gut bacteria. 10,89 stress and does not tolerate high-oxygen
Indole propionic acid A powerful antioxidant derived from tryptophan environments.
metabolism, protecting against oxidative stress and
inflammation. 89
(Cont'd...)

Volume 3 Issue 3 (2025) 27 doi: 10.36922/JCBP025040008