Microbiology Procedure

Index >> Bacterial Structure >> Functions of Fimbriae / Pili

Bacterial Structure
Part 1
Structure of Fimbriae or Pili
Functions of Fimbriae or Pili
Parts of Flagella
Bacterial Movement
Spirochaetal Movement
Gliding Movement
Nucleoid (Nucleus)
Plasmids
Classes of Plasmids
Gene Pickup and Sex Factors
R Plasmids
Plasmids Conferring Pathogenecity to mammals
Col Plasmids
Degradative Plasmids
Mercury Resistance Plasmids
Tumor Inducing Plasmid in Agrobacterium Tumifaciens
Cryptic Plasmids
Staphylococcal Plasmids

Functions of Fimbriae / Pili

	Functions of Fimbriae / Pili - The fimbriae and pili of bacteria serve multiple functions. The fimbriae are mainly associated with adhesive properties, which enable the organisms to attach themselves to natural substrates and to other individuals of their species. Fimbriated strains of E. coli are able to agglutinate erythrocytes, while the nonfimbriated strains are unable to do so. Fimbriated bacterial cells are able to attach themselves to erythrocytes, leucocytes, epithelial ce1ts and cell fragments of yeasts.
2. Fimbriae possess antigenic properties, and have been looked upon as constituting a thermolabile, non-type-specific agglutinogen. When fimbriated cells of Shigella flexnerii were injected into rabbits, the antiserum obtained produced a high degree of agglutination with fimbriated shigellas. A much slower and reduced action was obtained when the antiserum was tested against homologous nonfimbriated states of Shigella.
3. Cultures of many fimbriated bacteria(e. g E.coli, Salmonella typhimurium) can form a thin layer(pellicle)of cells or star-shaped aggregations on a static liquid medium. This property is due to the adhesiveness of the fimbriae, and is probably a device for an improved supply of atmospheric oxygen. Fimbriae seem to affect the metabolic activity of bacterial cells. In cultures of E coli K12 the respiratory activity of Fim+ cells is considerably greater than that of Pili- cells. This supports the view that fimbriae function as aggregation organelles and increase the oxygen supply by forming pellicles on the culture medium. Negative results have, however, been obtained by other workers.
4. The sex pili may provide the means of chromosome transfer during conjugation, probably by acting as conjugation tubes. Immuno-logical studies provide evidence that the tip of the pilus senses the female {P J cell and constitutes a specific site for attachment. It should be noted, however, that although an axial hole is present in the P-like pili, the I-pili do not appear to have such a hole. Moreover, no DNA bas ever been detected in the pili. The role of the pilus in transfer of DNA is therefore uncertain.

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