The environment represents the major source of prokaryotic (Eubacteria and
Archaebacteria) and eukaryotic (fungi, algae and phytoplankton) microorganisms that can
posses the ability to synthesize various microbial exopolysaccharides. Since the mid-19 th
century, when the dextran was found in the wine, the microbial exopolysaccharides have
received a growing attention due to their structural diversity that can supply a broad range
of physico-chemical, rheological and biological properties. Exopolysaccharides, known as
extracellular polysaccharides because they are secreted outside of the cells, are high
molecular weight polymers, that can be classified depending on the monomeric
composition into two groups: homopolysaccharides composed of a single type of
monosaccharides (dextran, levan) or heteropolysaccharides formed from two or more
repeating units of monosaccharides (xanthan, gellan, alginate and hyaluronic acid). Also,
microbial exopolysaccharides are produced in two basic forms: capsules and slime
polysaccharides. Industrial and technological advancement has led to the use of the
exopolysaccharides in various fields such as, food industry, waste water treatment,
bioremediation as well as in the pharmaceutical and biomedical fields. Antiulcer,
antitumor, anticoagulant and antiviral activities, anti-reflux therapies, cholesterol lowering
agents, surgical and ophtalmic applications, treatment of rheumatoid arthritis are some of
the health benefits of exopolysaccharides. The objective of this chapter is to make in
introduction a concise presentation of the structure and properties of the most popular
exopolysaccharides such as, dextran, curdlan, pullulan, xanthan gum, gellan gum,
hyaluronic acid and alginate followed by a discussion about their applications for treatment
and prevention of some diseases.
Keywords: Alginate, curdlan, dextran, exopolysaccharides, gellan gum,
hyaluronan, microbial polymers, pullulan, tissue engineering, xanthan gum.
