Enterobacteriaceae in the Human Gut: Dynamics and Ecological Roles in Health and Disease

Abstract

The human gut microbiota plays a crucial role in maintaining host health. Our review explores the prevalence and dynamics of Enterobacteriaceae, a bacterial family within the Proteobacteria phylum, in the human gut which represents a small fraction of the gut microbiota in healthy conditions. Even though their roles are not yet fully understood, Enterobacteriaceae and especially Escherichia coli (E. coli) play a part in creating an anaerobic environment, producing vitamins and protecting against pathogenic infections. The composition and residency of E. coli strains in the gut fluctuate among individuals and is influenced by many factors such as geography, diet and health. Dysbiosis, characterized by alterations in the microbial composition of the gut microbiota, is associated with various diseases, including obesity, inflammatory bowel diseases and metabolic disorders. A consistent pattern in dysbiosis is the expansion of Proteobacteria, particularly Enterobacteriaceae, which has been proposed as a potential marker for intestinal and extra-intestinal inflammatory diseases. Here we develop the potential mechanisms contributing to Enterobacteriaceae proliferation during dysbiosis, including changes in oxygen levels, alterations in mucosal substrates and dietary factors. Better knowledge of these mechanisms is important for developing strategies to restore a balanced gut microbiota and reduce the negative consequences of the Enterobacteriaceae bloom.

Keywords: Enterobacteriaceae; Escherichia coli; gut dysbiosis; human gut microbiota.

Figure 1

Mechanisms contributing to the expansion of Enterobacteriaceae in the dysbiotic gut. In conditions where high levels of oxygen reach the gut lumen, for example when enterocytes switch from mitochondrial fatty acid β-oxidation to anaerobic glycolysis, the facultative anaerobes of Enterobacteriaceae proliferate through aerobic respiration. In cases of gut inflammation, an increase in the availability of various electron acceptors promotes anaerobic respiration by Enterobacteriaceae. Changes in the gut environment caused by disease-associated dysbiosis can lead to Enterobacteriaceae expansion as a result of their adaptability to metabolize potential arising substrates. Created with Biorender.com.

Figure 2

Mechanisms of action of Enterobacteriaceae in the progression of inflammatory bowel diseases and obesity-associated diseases. LPS: lipopolysaccharides. Created with Biorender.com.