**2. Description of** *Salmonella*

*Salmonella* is a member of the Enterobacteriaceace, Gram negative, motile, with peritrichous flagella and nonsporeforming rods (the rods are typically 0.7-1.5 μm x 2.5 μm in size). *Salmonella* is a facultatively anaerobic (can grow with or without oxygen) catalase positive and oxidase negative bacteria. However, *Salmonella* is not included in the group of organisms referred to as coliforms (Huss & Gram, 2003; Adams & Moss, 2005; Erkmen, 2007; Lawley et al., 2008). These mesophilic organisms are distrubuted geographically all over the world, but principally occurring in the gastrointestinal tracts of mammals, reptiles, birds, and insects and environments polluted with human or animal excreta (Huss, 1994, Huss & Gram, 2003; Saeed & Naji 2007). Survival in water depends on many parameters such as biological (interaction with other bacteria) and physical factors (temperature). More than 2,500 different types of *Salmonella* exist, some of which cause illness in both animals and people. Some types cause illness in animals but not in people. The various forms of *Salmonella* that can infect people are referred to as serotypes, which are very closely related microorganisms that share certain structural features. Some serotypes are only present in certain parts of the world (Brands, 2006). For over 100 years *Salmonella* have been known to cause illness. The bacterium was first isolated from pigs suffering hog cholera by an American scientist, Dr. Daniel Elmer Salmon, in 1885 (Bremer et al., 2003).
