IMPROVED PRESERVATION OF BACTERIAL EXOPOLYMERS FOR SCANNING ELECTRON-MICROSCOPY

Two methods of sample preparation, originally developed for transmission electron microscopy and better at preserving bacterial exopolymers than the traditional fixation with glutaraldehyde, were adapted for scanning electron microscopy. The first involves a glutaraldehyde-lysine mixture as a fixative. The second, based on the use of polycationic ferritin, was modified to include a post-fixation step with either glutaraldehyde or a glutaraldehyde-lysine mixture. These techniques were found to improve considerably the preservation of exopolymers secreted by three bacterial strains.