Table 1.
Putative health-promoting and health-compromising characteristics and functions of the human gut microbiota.
| Characteristic | Effect |
|---|---|
| Health-promoting | |
| High species/genetic diversity | Associated with better health and resilience to perturbation |
| Bifidobacterium (phyla: Actinobacteria), Lactobacillus (phyla: Firmicutes) | Genera commonly used in probiotics; linked to multiple favorable health effects including increased resistance to infection and diarrheal disease, immune-enhancement, anti-carcinogenic, vitamin production, and secretion of anti-microbial compounds |
| Roseburia, Eubacterium, Clostridium clusters XIVa and IV (phyla: Firmicutes) | Butyrate producers |
| Faecalibacterium prausnitzii (phyla: Firmicutes) | Anti-inflammatory, butyrate producer |
| Increased butyrate production | Major energy source of colonocytes, anti-inflammatory, regulates cell growth and differentiation, anti-carcinogenic, improved gut barrier function, reduced colonic pH |
| Carbohydrate fermentation/increased short-chain fatty acid (butyrate, acetate, propionate) production | Reduced colonic pH, pathogen inhibition, anti-inflammatory, anti-carcinogenic, energy source for peripheral tissues, enhanced mineral absorption |
| Health-compromising | |
| Low diversity/high pathogen load | Compromised gut barrier integrity, local and systemic inflammation |
| Proteobacteria (includes family Enterobacteriaceae) | Phyla which produces pro-inflammatory lipopolysaccharide |
| Protein fermentation | Production of potentially carcinogenic/toxic compounds (N-nitroso compounds, amines, p-cresol, NH3, phenols, amines, thiols) |
| Sulfate/sulfite-reducing bacteria e.g., Bilophila wadsworthia, Desulfovibrio (phyla Proteobacteria) | Production of toxic H2S |
| Mucin degradation > synthesis | Compromises gut barrier integrity, facilitates bacterial translocation to epithelium, provides sulfates for H2S |