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From EcoliWiki

General information about Escherichia coli.

General Information

• Escherichia coli is a rod-shaped bacterium. Each bacterium measures approximately 0.5 μm in width by 2 μm in length. E. coli is a Gram-negative bacterium. E. coli cells stain Gram negative because they have a thin cell wall with only 1 to 2 layers of peptidoglycan. E. coli is a facultative anaerobe, which means it does not require oxygen, but grows better in the presence of oxygen.

• Much like "breeds" of dogs, there are "strains" of Escherichia coli. Many strains of E. coli are harmless and are important to good digestive health since they reside in the large intestine and provide their hosts with vitamin K.^[1][2] Other strains, which are referred to as pathogenic strains, are harmful and produce toxins.
• EcoliWiki is a resource for laboratory E. coli, which include non-pathogenic strains.
• Information from the Centers for Disease Control and Prevention about pathogenic and non-pathogenic E. coli
• Information about pathogenic E. coli in water sources from the Environmental Protection Agency (EPA)
• Information about pathogenic E. coli from the U.S. Food & Drug Administration (FDA)
• Information about research being performed on E. coli from the National Institute of Allergy and Infectious Diseases

Taxonomy

E. coli is a member of the:

• Bacteria;
  • Proteobacteria;
    • Gammaproteobacteria;
      • Enterobacteriales;
        • Enterobacteriaceae;
          • Escherichia.

Major subgroups

E. coli strains fall into five major taxonomic lineages (A, B1, B2, D, and E; ) ^[3]. In addition, species in the genus Shigella group within the E. coli groupings and different Shigella species have different E. coli groups as their closest relatives. E. coli K-12 strains are in subgroup A.

NCBI Taxonomy

E. coli at NCBI taxonomy encompasses a large number of strains with different taxonomy IDs.

• NCBI taxonomy
• NCBI taxonomy nodes

As of January 2010, the groupings in the NCBI taxonomy do not reflect the major groupings of E. coli and Shigella strains.

Laboratory E. coli strains

Major E. coli lab strains used for basic research are mostly derived from E. coli K-12 and E. coli B.

E. coli K-12

Note that correct usage is K-12, not K12. E. coli K-12 is not serotype K.

E. coli B

Daegelen ^[4] examined the literature to derive what is known about the geneology of E. coli B strains. Current E. coli B strains are derived from the E. coli used in the phage studies of the Luria, Delbruck, and Hershey groups associated with the Cold Spring Harbor Phage community.

Morphology

E.coli negatively stained with Ammonium Molybdate and analyzed by EM (electron microscopy). Image courtesy of Christos Savva (Microscopy & Imaging Center) and Thomas Wood (Dept. of Chemical Engineering) at Texas A&M University.

cryo-EM picture of E.coli (dark blobs are hexagonal ice crystals). Image courtesy of Christos Savva (Microscopy & Imaging Center) and Ry Young (Dept. of Bio/Bio) at Texas A&M University.

Types

E. coli types are based on major surface antigens^[5]

• O-antigen: the O antigen is part of the lipopolysaccharide. O antigens were originally defined by reaction with antisera from rabbits immunized with boiled bacteria. Hundreds of O groups have been identified.
• H-antigen: H antigen is flagellin
• K-antigens: K antigens were named for capsule (Kapsel in German). Sera subdivide K antigens into L, B, and A groups. At the molecular level, there are two major kinds of K antigens
  • polysaccharide K antigens
  • protein K antigens, mostly fimbriae
• R-antigen:

Chemical Composition

From Neidhardt^[7] based on B/r.

Educational Resources

• EcoliWiki & Education
• Education links on EcoliWiki
• EcoliWiki Methods
• ASM CUE
• National Science Teachers Association
• National Association of Biology Teachers

Other E. coli Sequencing Projects

There are roughly 200 completed or ongoing sequencing projects for strains of E. coli. While this list continues to grow, some are listed here on EcoliWiki and NCBI has a complete list.

See also

• EcoliHub
• EcoCyc
• Stanford Microarray Database
• EcoSal (subscription required)
• E. coli at Wikipedia
• Gene lists
• CGSC - The Coli Genetic Stock Center

References

See Help:References for how to manage references in EcoliWiki.

1. ↑ Cummings JH & Macfarlane GT (1997) Role of intestinal bacteria in nutrient metabolism. JPEN J Parenter Enteral Nutr 21: 357-65 PubMed EcoliWiki page
2. ↑ Kindberg C et al. (1987) Menaquinone production and utilization in germ-free rats after inoculation with specific organisms. J Nutr 117: 1032-5 PubMed EcoliWiki page
3. ↑ Touchon M et al. (2009) Organised genome dynamics in the Escherichia coli species results in highly diverse adaptive paths. PLoS Genet 5: e1000344 PubMed EcoliWiki page
4. ↑ Daegelen P et al. (2009) Tracing ancestors and relatives of Escherichia coli B, and the derivation of B strains REL606 and BL21(DE3). J Mol Biol 394: 634-43 PubMed EcoliWiki page
5. ↑ Orskov I et al. (1977) Serology, chemistry, and genetics of O and K antigens of Escherichia coli. Bacteriol Rev 41: 667-710 PubMed EcoliWiki page
6. ↑ Liu D & Reeves PR (1994) Escherichia coli K12 regains its O antigen. Microbiology 140 ( Pt 1): 49-57 PubMed EcoliWiki page
7. ↑ Neidhardt, FC et al. (1996) Escherichia coli and Salmonella typhimurium: Cellular and Molecular Biology (ASM Press, Washington, DC)