Microorganisms biofilms defined

Rrnax is a function of the active microorganism concentration in the biofilm and is defined as ... 

The resident microbes within the mouth readily form biofilms on teeth. A biofilm consists of a population of bacteria coexisting in an orderly structure at the interface of a solid and a liquid [14] and, within a biofilm, bacteria living in colonies encapsulated in a matrix of extracellular polymer. Oral biofilms are known to vary extensively in structure throughout the colony, with regions of densely packed microorganisms surrounded by open water channels. Each type of bacteria exists in reasonably defined environments which are influenced by surrounding cells, distance from the outer surface and local structure, all of which influence availability of nutrients and ambient pH. 

The film that forms on the surface is very complex physically and microbiolog-ically, but it is useful to conceptualize the film as a simple model (see Figure 5.3). The cells are embedded in this hydrogel coating. The substratum (left) will be defined later. For now we will consider it inert and nonabsorptive. The biofilm layer is a complex composite of the microorganism and a hydrogel vehicle. The phase immediately in contact with the biofilm is called the boundary layer. 

Biofilms are abundant in a multitude of aquatic environments in which they cover all kinds of inorganic and organic solid surfaces. Biofilms can be defined as microorganisms attached to a surface and embedded in an extracellular gellike matrix of polymeric substances. This matrix is excreted by the microorganisms themselves and may be enriched by molecules adsorbed from the surrounding water. 

The other major application for biocides in the oilfield is in biofouling control. This can be defined as the use of a biocide to kill microorganisms that are present in the water that is either injected into an oilfield, or the water that is produced from the oilfield. The reason that biocides are used is to kill the microorganisms before they have the opportunity to attach to the metal surfaces and form biofilms. Considerations on the use of biocides in the injection and production systems are discussed below. 

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