why do bacteria in a biofilm have different characteristics than free-floating bacteria
Biofilm Bacteria living in a biofilm usually have significantly different properties from free-floating bacteria of the same species, as the dense and protected environment of the film allows them to cooperate and interact in various ways.[34] One benefit of this environment is increased resistance to detergents and antibiotics, as the dense extracellular matrix and the outer layer of cells protect the interior of the community. In some cases antibiotic resistance can be increased a thousandfold.[35] Lateral gene transfer is often facilitated within bacterial and archaeal biofilms[36] and leads to a more stable biofilm structure.[37] Extracellular DNA is a major structural component of many different microbial biofilms.[38] Enzymatic degradation of extracellular DNA can weaken the biofilm structure and release microbial cells from the surface.
Bacteria The ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, about 4 billion years ago. For about 3 billion years, most organisms were microscopic, and bacteria and archaea were the dominant forms of life.[20][21] Although bacterial fossils exist, such as stromatolites, their lack of distinctive morphology prevents them from being used to examine the history of bacterial evolution, or to date the time of origin of a particular bacterial species. However, gene sequences can be used to reconstruct the bacterial phylogeny, and these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage.[22] The most recent common ancestor of bacteria and archaea was probably a hyperthermophile that lived about 2.5 billionâ€“3.2 billion years ago.[23][24]