Antigen 43 and type 1 fimbriae determine colony morphology of Escherichia coli K-12

J Bacteriol. 2000 Feb;182(4):1089-95. doi: 10.1128/JB.182.4.1089-1095.2000.


Colony morphology has been used as an important identification and characterization criterion in bacteriology for many decades. However, the molecular mechanisms underlying the appearance of different colony types have been given little attention. The synthesis of O antigen is defunct in Escherichia coli K-12, and colonies should accordingly only appear to be rough. However, previous reports have noted the presence of different interchangeable colony morphology types. In this study we have addressed the influence of two phase-variable surface structures, antigen 43 and type 1 fimbriae, on colony morphology. Due to differential expression of these structures, four different colony phenotypes could be distinguished. By creating and studying defined mutants of the respective loci, i.e. , flu and fim, we conclude that the presence or absence of the corresponding gene products on the cells correlates with the observed colony morphology forms. Interestingly, the habitat specificity of bacteria under static liquid conditions seems to correlate with the colony phenotypes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adhesins, Bacterial*
  • Adhesins, Escherichia coli
  • Antigens, Bacterial*
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / physiology*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / physiology*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / physiology*
  • Escherichia coli / cytology*
  • Escherichia coli / genetics*
  • Escherichia coli / growth & development
  • Escherichia coli Proteins*
  • Fimbriae, Bacterial / genetics
  • Fimbriae, Bacterial / physiology*
  • Microscopy, Fluorescence
  • Mutation
  • Plasmids / genetics


  • Adhesins, Bacterial
  • Adhesins, Escherichia coli
  • Antigens, Bacterial
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • antigen 43, E coli
  • fimE protein, E coli