Commensal and Pathogenic Escherichia coli Metabolism in the Gut

Abstract

E. coli is a ubiquitous member of the intestinal microbiome. This organism resides in a biofilm comprised of a complex microbial community within the mucus layer where it must compete for the limiting nutrients that it needs to grow fast enough to stably colonize. In this article we discuss the nutritional basis of intestinal colonization. Beginning with basic ecological principles we describe what is known about the metabolism that makes E. coli such a remarkably successful member of the intestinal microbiota. To obtain the simple sugars and amino acids that it requires, E. coli depends on degradation of complex glycoproteins by strict anaerobes. Despite having essentially the same core genome and hence the same metabolism when grown in the laboratory, different E. coli strains display considerable catabolic diversity when colonized in mice. To explain why some E. coli mutants do not grow as well on mucus in vitro as their wild type parents yet are better colonizers, we postulate that each one resides in a distinct “Restaurant” where it is served different nutrients because it interacts physically and metabolically with different species of anaerobes. Since enteric pathogens that fail to compete successfully for nutrients cannot colonize, a basic understanding of the nutritional basis of intestinal colonization will inform efforts to develop prebiotics and probiotics to combat infection.

Quorum Sensing Regulators Are Required for Metabolic Fitness in Vibrio parahaemolyticus

“…The gene expression data suggested that the luxO mutant could have metabolic defects based on the downregulation of key metabolism genes. Competition for intestinal nutrients and the ability to utilize intestinal mucus as a carbon and energy source have been shown to be important for successful colonization of intestinal bacteria (56)(57)(58)(59). Phenotypic array data showed that the deletion of luxO resulted in metabolic defects, with the mutant demonstrating a defect in growth on a number of carbon sources.…”

Glycolysis and pyrimidine biosynthesis are required for replication of adherent–invasive Escherichia coli in macrophages

“…Indeed different strains of E. coli appear to have different metabolic requirements for colonization, and E. coli strains with similar metabolic requirements appear to compete to occupy the same niche in the gut of the host (i.e. the restaurant hypothesis) (Conway & Cohen, 2015;Maltby et al, 2013). Previous work has also shown that gluconeogenesis and the TCA cycle are important for the growth of uropathogenic E. coli (UPEC) in urine (Alteri et al, 2009).…”

Escherichia coli O157:H7 Strain EDL933 Harbors Multiple Functional Prophage-Associated Genes Necessary for the Utilization of 5- N -Acetyl-9- O -Acetyl Neuraminic Acid as a Growth Substrate

“…However, they are actually in equilibrium with the turnover rate of mucus. One possibility is explained in the "Restaurant" hypothesis, which implies that E. coli bacteria grow in synergy with gut anaerobes which can degrade large polysaccharide chains to mono-or disaccharides (34). Indeed, it was shown that commensal E. coli strain MG1655 as well as E. coli O157:H7 strain EDL933 can grow well on mucus-derived saccharides such as N-acetylglucosamine, gluconate, galactose, N-acetyl neuraminic acids, and others (39).…”

“…Furthermore, E. coli O157:H7 needs mechanisms to avoid host defense and to penetrate the mucus layer to reach the gut epithelium (34). Human gastrointestinal mucus consists of two layers, a thick loosely mucus layer and a thinner layer attached to the mucosa (35).…”