Glycolytic and Gluconeogenic Growth of Escherichia coli O157:H7 (EDL933) and E. coli K-12 (MG1655) in the Mouse Intestine

Abstract

Infect. Immun. 58: [2438][2439][2440][2441][2442][2443][2444][2445] 1990), but what nutrients and metabolic pathways are employed during colonization has not been determined. In this study, when the wild-type EDL933 strain was fed to mice along with an EDL933 ⌬ppsA ⌬pckA mutant, which is unable to utilize tricarboxylic acid cycle intermediates and gluconeogenic substrates for growth, both strains colonized the mouse intestine equally well. Therefore, EDL933 utilizes a glycolytic substrate(s) for both initial growth and maintenance when it is the only E. coli strain fed to the mice. However, in the presence of large numbers of MG1655, a K-12 strain, it is shown that EDL933 utilizes a glycolytic substrate(s) for initial growth in the mouse intestine but appears to utilize both glycolytic and gluconeogenic substrates in an attempt to maintain colonization. It is further shown that MG1655 predominantly utilizes glycolytic substrates for growth in the mouse intestine whether growing in the presence or absence of large numbers of EDL933. Data are presented showing that although small numbers of EDL933 grow to large numbers in the intestine in the presence of large numbers of MG1655 when both strains are fed to mice simultaneously, precolonization with MG1655 affords protection against subsequent colonization by EDL933. Moreover, in mice that are precolonized with EDL933, small numbers of MG1655 are able to grow rapidly in the intestine and EDL933 is eliminated. In situ hybridization experiments using E. coli-specific rRNA probes showed that while MG1655 is found only in mucus, EDL933 is found both in mucus and closely associated with intestinal epithelial cells. The data are discussed with respect to competition for nutrients and to the protection that some intestinal commensal E. coli strains might afford against infection by O157:H7 strains.Escherichia coli strains of serotype O157:H7 cause outbreaks of hemorrhagic colitis and hemolytic uremic syndrome in humans (reviewed in reference 14). E. coli O157:H7 initiates infection by binding to intestinal epithelial cells and producing Shiga toxins Stx1 and/or Stx2, depending on the strain (reviewed in reference 14). Stx1 and Stx2 depurinate a critical residue in the eucaryotic 28S rRNA of 60S ribosomes, resulting in the inhibition of protein synthesis and consequent cell death (33). E. coli EDL933, an O157:H7 strain, does not normally kill streptomycin-treated mice and appears to colonize the mouse intestine by growing in intestinal mucus (38, 40), but little is known about the nutrients that are utilized for growth or the metabolic pathways involved. If these pathways were defined, it is likely that preventative measures or more effective treatments for patients infected with O157:H7 strains could be developed. With this goal in mind, we isolated an EDL933 ⌬ppsA ⌬pckA mutant, which grows normally on glycolytic substrates but is unable to utilize tricarboxylic acid (TCA) cycle intermediates and gluconeogenic substrates for growth, and tested its ability to colonize the m...

Enterohemorrhagic Escherichia coli Virulence Gene Regulation

“…Carbohydrate recognition and metabolism are important for EHEC niche adaptation (30) and ensure that EHEC virulence proteins are expressed only at the appropriate site of infection. A glycolytic environment, at 0.4% glucose, inhibits ler and LEE expression, whereas 0.1% glucose mimicking gluconeogenesis conditions enhances their expression (31).…”

Proteins differentially expressed by Shiga toxin-producing Escherichia coli strain M03 due to the biliar salt sodium deoxycholate

“…For intestinal pathogens such as STEC, once ingested by a host they must successfully colonize the host intestinal mucosa to cause disease. These pathogenic strains of E. coli have acquired metabolic and virulence genes that enable them not only to compete successfully with the indigenous microbiota of the intestine but also to occupy new niches (Miranda et al, 2004;Fabich et al, 2008;Fuchs et al, 2012). To survive in the human gastrointestinal tract, microorganisms must respond to several environmental extreme conditions such as pH variations, low oxygen levels, nutrient limitation, elevated osmolarity and exposure to bile, all of which constitute potential impediments to survival.…”

Escherichia coli Isolate for Studying Colonization of the Mouse Intestine and Its Application to Two-Component Signaling Knockouts

“…This streptomycin-treated mouse model has played a key role in the characterization of the growth of E. coli in the intestine and the identification of nutritional and metabolic requirements for colonization (10,(12)(13)(14)(15)(16). The model has been particularly effective because it not only overcomes colonization resistance-the barrier to establishing an infection in an animal whose microbial flora is unperturbed-but also enables colonization with strains that would otherwise be unable to compete with bacteria that are well adapted to the host (10,11,17).…”