Proteobacteria / Pseudomonadota

Pseudomonadota are common in the human gut. They include many pathogens. These pathogens use secretion systems injecting proteins into host cells. 80% of Pseudomonadota in healthy guts have type III secretion systems (T3SS). Machine learning predicts candidate effectors. These effectors have unique sequence and structure.
Young et al. 2026 Nat Microbiol 11: 442-460

Most proteobacteria are flagellated.

Proteobacteria involve Escherichia and Desulfovibrio.
Antonini et al. 2019 Front. Immunol. 10: 1937

The Proteobacteria showed relatively high abundance in genes involved in degradation of xenobiotics (ko01220), possibly contributing to the degradation of environmental chemicals and pharmaceuticals in the gut
Zou et al. 2019b Nat Biotechnol 37: 179-185

Relative abundance of Proteobacteria in the ecosystem

• Soil: 36.5%


• Plant leaf: 62.0%


• Air: 77.9%


• Ocean: 57.9%


• Freshwater: 61.3%


• Human gut: 4.5%

Shin et al. 2015 Trends Biotechnol 33: 496

The healthy adult has very little Proteobacteria in the gut microbiota. Only in the newborn age does the proportion temporarily reach 16% of the total intestinal bacteria. However, in diseases such as metabolic disorders (e.g., obesity), inflammation, and cancer, the proportion of Proteobacteria increases to 13-15%. An imbalanced gut microbiota often arises from a sustained increase in abundance of the phylum Proteobacteria.
Shin et al. 2015 Trends Biotechnol 33: 496

Proteobacteria show an ability to adhere to and invade gut epithelial cells
Mukhopadhya et al. 2012 Nat Rev Gastroenterol Hepatol. 9: 219–230

see also:
Pseudomonas syringae & Type III Secretion Systems (T3SS)