ABSTRACT

The normal tendency of a microbial cell (bacteria, yeast, molds) when it comes in contact with a solid surface is to attach itself to the surface in an effort to compete efficiently with other microbial cells for space and the nutrient supply and to resist any unfavorable environmental conditions. The solid surface may be comprised of a biotic, that is, biological, such as meat, fruits, etc., or abiotic surface (nonbiological), such as floors, walls, pipes, drains, equipment, or food contact surfaces (conveyor belts, pasteurizers, gaskets). Under suitable conditions, almost all microbial cells can attach to a solid surface, which is achieved through their ability to produce extracellular polysaccharides. As the cells multiply, they form a three-dimensional scaffold, forming a biofilm on the surface containing a community of microbial cells, a polyanionic extracellular polymeric substance (EPS), and entrapped debris. The EPS may contain polysaccharide-glycocalyx, proteins, phospholipids, teichoic and nucleic acids, and other polymeric substances. 1 In some situations, instead of forming a biofilm, the cells may attach to contact surfaces and other cells by thin, threadlike exopolysaccharide materials, also called fimbriae. Biofilms are comprised of a single species or a mixed species culture with one being dominant.