Growth of Salmonella typhimurium SL5319 and Escherichia coli F-18 in mouse cecal mucus: role of peptides and iron

Franklin, David P.; Laux, David C.; Williams, Taffy J.; Falk, Michael C.; Cohen, Paul S.

doi:10.1111/j.1574-6941.1990.tb01688.x

Cited by 10 publications

(10 citation statements)

References 19 publications

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“…Our results are supported by previous findings showing that the human isolate E. coli F18 grows with a generation time of about 27 min in mouse intestinal mucus in vitro but does not grow in cecal contents or feces (11,38). The main source of carbon and nitrogen was found to be a phospholipid, secreted by the host, which is abundant in intestinal mucus (20).…”

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confidence: 82%

“…The streptomycintreated mouse was used as the model animal, mainly because bacterial colonization of this animal model has been studied in great detail (11,20,29,38) but also because previous investigations showed that E. coli may not be such a frequent colonizer of conventional animals (35) and it is very unlikely that an introduced E. coli culture would become established in a conventional animal. This, however, means that our conclusions may be true only for streptomycin-treated mice, and we are therefore planning future experiments with germ-free and conventional mice.…”

Section: Discussionmentioning

confidence: 99%

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Physiological state of Escherichia coli BJ4 growing in the large intestines of streptomycin-treated mice

et al. 1995

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Growth rates of Escherichia coli BJ4 colonizing the large intestine of streptomycin-treated mice were estimated by quantitative hybridization with rRNA target probes and by epifluorescence microscopy. The ribosomal contents in bacteria isolated from the cecal mucus, cecal contents, and feces were measured and correlated with the ribosomal contents of bacteria growing in vitro at defined rates. The data suggest that E. coli BJ4 grows at an overall high rate in the intestine. However, when taking into account the total intestinal volume and numbers of bacteria present in cecal mucus, cecal contents, and feces, we suggest that E. coli BJ4 in the intestine consists of two populations, one in the mucus which has an apparent generation time of 40 to 80 min and one in the luminal contents which is static.The animal intestinal tract harbors a vast number of bacteria representing a complex ecosystem in which the microorganisms are present without overgrowing the host but also without being flushed out by the host's intestinal activities, e.g., peristaltic movements and fluid flow. At least 400 to 500 different bacterial species are thought to be present at any time in the healthy human intestinal tract, and up to 10 12 bacteria are found per g of feces (3, 9). One question of interest is whether the intestinal flora grows as a homogeneous population at a low rate or as a heterogeneous population containing fast, slow, and nongrowing organisms.Accurate calculations of the rates of bacterial proliferation in the intestine have so far been represented only by average estimates at the level of populations. For example, the growth rate of Escherichia coli has been estimated in vivo, i.e., in the mouse intestine, by radioisotope techniques (8), by dilution by growth of a nonreplicating genetic marker (17,25), and simply by counting the number of viable cells (12,14). With these techniques, generation times from 30 min to 40 h have been estimated for E. coli (12,14,16,36). Also, continuous-flow cultures have been developed to mimic bacterial interactions in the gut and estimate overall growth rates (13, 27). These systems, however, do not reflect the physiological conditions in the gut, where entrapping of the bacteria in the mucus gel plays an important role. Furthermore, bacterial cell morphology, protein profiles, and growth physiology have been found to be distinct during growth in the intestine when compared with growth in laboratory media (22,33).We have previously found that in test tubes E. coli BJ4 is rod shaped, appears as large cells, and has a great potential for fast growth; however, soon after colonization of mice, E. coli BJ4 differentiates into a coccoid morphology, the so-called small variant, which grow more slowly than the rod-shaped E. coli cells in aerated test tubes (22). Here, we continue our investigation of the growth physiology of E. coli BJ4 present in its natural environment, the large intestine. Bacterial growth rates can be estimated from the cellular RNA and/or DNA contents, since the cellular RNA...

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confidence: 82%

Section: Discussionmentioning

confidence: 99%

Physiological state of Escherichia coli BJ4 growing in the large intestines of streptomycin-treated mice

et al. 1995

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“…To this point, the data suggested that MG1655 ⌬edd utilizes not only gluconate poorly relative to MG1655 but a number of other carbon sources as well. In addition, at some point after mice were fed MG1655 ⌬edd, it appeared that the mouse intestine selected better-colonizing mutants, among them MG1655 ⌬edd*, that were better able to grow on at least some of the sugars known to be present in mouse cecal mucus and utilized for growth in the intestine, i.e., fucose, gluconate, N-acetylglucosamine, glucuronate, mannose, and ribose (8,13). It was therefore of interest to determine whether the mouse intestine would also select a mutant of the original wild-type MG1655 strain that was a better colonizer and grew faster than the original MG1655 strain on a variety of carbon sources.…”

Section: Resultsmentioning

confidence: 99%

Mouse Intestine Selects Nonmotile flhDC Mutants of Escherichia coli MG1655 with Increased Colonizing Ability and Better Utilization of Carbon Sources

et al. 2005

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D-Gluconate which is primarily catabolized via the Entner-Doudoroff (ED) pathway, has been implicated as being important for colonization of the streptomycin-treated mouse large intestine by Escherichia coli MG1655, a human commensal strain. In the present study, we report that an MG1655 ⌬edd mutant defective in the ED pathway grows poorly not only on gluconate as a sole carbon source but on a number of other sugars previously implicated as being important for colonization, including L-fucose, D-gluconate, D-glucuronate, N-acetyl-D-glucosamine, D-mannose, and D-ribose. Furthermore, we show that the mouse intestine selects mutants of MG1655 ⌬edd and wild-type MG1655 that have improved mouse intestinecolonizing ability and grow 15 to 30% faster on the aforementioned sugars. The mutants of MG1655 ⌬edd and wild-type MG1655 selected by the intestine are shown to be nonmotile and to have deletions in the flhDC operon, which encodes the master regulator of flagellar biosynthesis. Finally, we show that ⌬flhDC mutants of wild-type MG1655 and MG1655 ⌬edd constructed in the laboratory act identically to those selected by the intestine; i.e., they grow better than their respective parents on sugars as sole carbon sources and are better colonizers of the mouse intestine.

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“…Possibilities for gluconeogenic substrates that EDL933 utilizes in mucus include the amino acids aspartate and tryptophan, which can serve as sole carbon sources for E. coli growth (19). Free amino acids are found in mouse cecal mucus (7). In addition, phosphatidylserine, present at a relatively high concentration in mouse cecal mucus preparations scraped from the intestinal wall (17), has been shown to serve as a sole source of carbon for the growth of EDL933 (17).…”

Section: Discussionmentioning

confidence: 99%

“…The two components of the mucosa are the layer of epithelial cells on the intestinal wall and the mucus layer, which covers them. The relatively thick (up to 400 m) mucous layer consists of mucin, a 2-MDa gel-forming glycoprotein, and a large number of smaller glycoproteins, proteins, glycolipids, lipids, and sugars (1,6,7,16,28,29,31,34). Presumably, shed epithelial cells are a source of many of the smaller mucous components (29,31).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2004

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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...

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Growth of Salmonella typhimurium SL5319 and Escherichia coli F-18 in mouse cecal mucus: role of peptides and iron

Cited by 10 publications

References 19 publications

Physiological state of Escherichia coli BJ4 growing in the large intestines of streptomycin-treated mice

Physiological state of Escherichia coli BJ4 growing in the large intestines of streptomycin-treated mice

Mouse Intestine Selects Nonmotile flhDC Mutants of Escherichia coli MG1655 with Increased Colonizing Ability and Better Utilization of Carbon Sources

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

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