ABSTRACT
The bacterial polysaccharide is isolated from the broth following the usual method adopted in our laboratory [6].
Some comments on this procedure are necessary: the solution (the broth or diluted broth) after centrifugation to remove the solids in suspension must be filtered through porous membranes with decreasing porosity down to 0.45 Am to suppress not only solid material but also aggregated molecules. The first precipitationwith ethanol is performed in the presence of a salt excess (usually NaCl) to exchange the divalent counterions and recover the sodium salt ofHA, which must be perfectly water soluble in these conditions. The presence of divalent counterions modifies the hyaluronan properties in solution [7,8] and they must be removed. If necessary, a second precipitation can be achieved.
