Microbial polysaccharides

Microorganisms are a rich and as yet underexploited source of exopolysaccharides (EPS). These complex molecules serve as energy reserves, structural materials and stores of information, and are involved in molecular interaction and recognition. Although plants produce a wide range of polysaccharides, their diversity is considerably less than that of those produced by micro-organisms. The number of different sugars found in polysaccharides is an indicator of diversity of structure and some 200 different sugars have been found in microbial polysaccharides, compared to approximately 25 associated with those of plant origin1. As the structure and function of these biofunctional molecules become known, microorganisms will become important as sources of them and will in addition provide the means of producing them from other diverse sources using molecular genetic methods already available. In the short term, however, industrial applications of microbial polysaccharides will be confined to their use as Theological modifiers of aqueous solutions. The wide range of structures, their properties and potential applications have been the subject of a number of reviews2–10. This review will focus on the production and applications of microbial polysaccharides that are in commercial use and discuss the prospects for those approaching commercialization in the food, oilfield and industrial areas.