Novel and established applications of microbial polysaccharides.

Microbial exopolysaccharides such as xanthan and dextran have been commercial products for many years; the search for new gelling agents has yielded gellan. Exopolysaccharides have many other novel properties to offer, and the discovery of immune modulation and tumouristasis by beta-D-glucans, and the use of bacterial cellulose in audio membranes and of hyaluronic acid in cosmetics provide some novel applications. Semisynthetic polymers and polysaccharides as sources of oligosaccharides and as enzyme substrates in the determination of enzyme specificity should further increase the interest in these macromolecules.