Bacterial cell appendages

Three types of thread-like appendages may be found growing from bacterial cells flagella, pili (fimbriae) and F-pili (sex strands). 

Many bacterial cells have appendages used for movement called flagella. Some cells also have pill, which are a protein strand used for attachment of the bacteria. Pili may also be used for sexual conjugation (where the DNA from one bacterial cell is transferred to another bacterial cell). 

Virtually all bacterial species and genera express lectins or lectin-like activities, frequently of more than one type and with different specificities. However, it is usually not known whether individual cells coexpress multiple types of lectin or each lectin is confined to a distinct cell population. Many Gram negative bacteria (for example, Escherichia coli and Salmonellae spp.) and a few Gram positive ones (e.g. certain actinomyces), produce surface lectins that are often in the form of submicroscopic hairlike appendages known as fimbriae (pili) that protrude from the surface of the cells. The best characterized bacterial surface lectins with respect to their molecular properties, carbohydrate specificity and genetics are the type 1 fimbriae specific for mannose and the type P fimbriae specific for galabiose, [Gal(al-4)Gal], produced by many strains of E. coli. Other examples are S fimbriae of E. coli, specific for NeuAc(a2-3)Gal, and type 2... 

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