Figure 4.

Potential routes for the formation of microcolonies

Microcolony formation arises from the accumulation of cells in continuous growth and division and may be enhanced by the incorporation of planktonic cells from the bulk fluid or product of cell division and the integration of bacterial clusters. (1) Once bacteria become strongly attached, the colonization of the surface takes place by means of cell growth and division. One of the daughter cells may remain attached, and the other may be released from the surface (3A), where it becomes free to colonize other sites (2) by landing onto target surfaces (3B) or, it may become part of recently formed bacterial clusters either on the surface (3C) or the bulk fluid (3D). Bacterial clusters formed in the absence of a solid substrate may colonize new surfaces or land onto biofilms under development (3E). During cell proliferation and biofilm formation, QS signals and production of EPS matrix occur. As cell density increases, some of the bacteria slide along each other (3F) leading to the formation of small bacterial aggregates, which correspond to “immature” biofilms known as microcolonies (4).