Effects of polymyxin B on the outer membranes of Aeromonas species

Abstract

The effect of polymyxin B on the outer membranes of the Gram negative bacteria Aeromonas spp. was examined and compared with the outer membranes prepared by breaking cells by the conventional method of osmotic shock and subsequent solubilization with sodium lauryl sarcosinate (Sarkosyl). SDS profiles of the two preparations revealed differences but immunoblot analysis showed close-to-similar profiles. The striking difference which the preparations revealed was the absence of smearing in the polymyxin treated ones. The same was also revealed when the two methods were appled on a slightly larger scale to a survey analysis done with 14 strains of the three species of Aeromonas - A. hydrophila, A. sobria and A. caviae. The results of this study indicate that apart from being a fast and convenient method for extracting outer membranes, application of polymyxin B is useful in removing lipopolysaccharide from outer membranes when applied to viable cells.