- "What being in a biofilm means to bacteria

Lots of bacteria are planktonic – they float around in water; microbiologists since the time of Pasteur have conducted most bacterial studies using suspended bacterial cultures.

But most of the bacteria that cause us problems are sessile – attached to a surface – and they live in biofilms. Once bacteria attach to a surface, they change. The most obvious change is that they begin to excrete a slimy material (which has provided the basis for coining the word biofilm). But we are learning that other changes made by attached bacteria are profound, though invisible. In fact, researchers have now shown that a bacterium which attaches to a surface "turns on" a whole different set of genes, which makes it effectively a significantly different organism to deal with. If researchers continue to study cells in suspended cultures, when the actual problems involve biofilm bacteria, the control strategies derived from the studies will target what, phenotypically, amounts to the wrong organism!

The CDC implicates biofilms in 65% of human bacterial infections. Bacterial biofilms also cause fouling, product contamination, equipment failure, and decreased productivity due to downtime for system cleaning and replacement. We have plenty of evidence that control strategies based on suspended cells are less effective on biofilm cells. Antibiotic doses which kill suspended cells, for example, need to be increased as much as 1,000x to kill biofilm cells (and these amounts would kill the patient first!). Disinfection rates for biofilm cells are also far below planktonic kills by antimicrobials.

But wait. . . there's more!

Biofilm bacterial behavior is much more complex than suspended cell behavior, because biofilm bacteria live in communities. According to the CBE's Dr. Gill Geesey, recent studies have revealed that there are significant differences in the level of expression of genes involved in nutrient cycling among members of a single species bacterial population exposed to the same apparent conditions. Within these populations, there appears to be "division of labor" whereby some cells utilize available energy to turn on metabolic pathways that effect partial degradation of dead particulate matter, while other adjacent cells of the same population utilize the degradation products to produce new cells that are dispersed in the environment.

more at: http://www.erc.montana.edu/CBEssentials-SW/bf-basics-99/bbasics-bfcharact.htm