IMAGING BACTERIAL POLYSACCHARIDES BY AFM

Atomic force microscopy has been used to image the bacterial polysacch arides xanthan, acetan and gellan. Images were obtained under constant force conditions in a liquid cell. Drops of dilute solutions of the p olysaccharides were deposited onto freshly cleaved surfaces of mica an d allowed to dry in air. The deposits were then imaged under butanol. Xanthan and acetan form entangled networks upon deposition. Individual molecules can be identified. Under suitable circumstances it has been possible to image the helical structure of acetan. Gellan forms gels upon concentration during drying and images have been obtained of the gel network.