Abstract

Salmonella species are the members of Enterobacteriaceae family, these organisms are gram- negative flagellated bacillus and most of their serotype except Salmonella gallinarum and Salmonella pullorum are motile. Lipopolysaccharide in gram-negative bacteria has the complex construction and is composed of three parts including the complex part named fat A, polysaccharide, and side chain O. There are different methods for extraction, separation and purification of LPS which are expensive or poisonous and less safe. In this study, the methanol-chloroform method is introduced because it saves time, expense and lack of usaging phenol. Lipopolysaccharide of S. typhimurium and S. Enteritidis were extracted using methanol-chloroform method. The extracts were compared with standard lipopolysaccharide via SDS-PAGE following silver staining. Pyrogenicity effect of Salmonella lipopolysaccharide was studied on 12 rats by using 100 and 150 µg/kg of LPS. The results showed that extracted bands out of lipopolysaccharide of both bacteria, is same as their standard. The LPS extract of Salmonella typhimurium revealed increasing of rat body temperatures (1 to 2°C) in both 100 and 150 µg/kg dosages after 2 h treatment. While the rat body temperature increases by the dose of 150 µg/kg, higher than the dose of 100 µg/kg. Considering the results, lipopolysaccharide bands extracted by usingmethanol-chloroform method and comparing them with standard samples could be a proper method with less expense, and much safety in comparison with the other methods and also it has a very high yield.

Key word: Salmonella, lipopolysaccharide, SDS-PAGE.