Ultrastructure of Staphylococcus aureus as revealed by microwave fixation

The ultrastructure of the cell wall of Staphylococcus aureus was examined at electron microscopic level using new chemical fixation techniques during microwave irradiation and the results obtained were compared with those obtained by other conventional techniques. By using microwave fixation the concentric circular or zipper-like structure was observed in the cell wall. This structure was observed also with the spray-freeze-etch technique but not in thin section of the cells chemically fixed by conventional technique. For chemical fixative, glutaraldehyde is more advantageous than OsO4 as a concomitant fixative during microwave irradiation and postfixation by OsO4 is unnecessary and rather harmful for the preservation of the ultrastructure. The function of the observed structure is briefly discussed.