Detection of lipopolysaccharide components in isolated outer membranes of Serratia marcescens

The lipopolysaccharide (LPS) component in outer membranes isolated from two strains of S. marcescens was specifically detected and identified by a staining technique using carbocyanine dye after polyacrylamide electrophoresis. Two LPS containing components were found in the outer membrane fractions. The major component was shown to have an apparent molecular weight of 12,000 daltons and was associated with a protein component of the outer membrane. The carbocyanine dye was found to be more sensitive and specific for LPS than other common stains used for the detection of carbohydrates and proteins. The potential of this technique for the quantitative measurement of the LPS content directly from outer membranes was discussed.