Industrial uses of microbial polysaccharides

Abstract

Both microbial and non-microbial polysaccharides find a wide range of nonfood industrial uses. In such usage, the polysaccharides may compete with synthetic organic polymers, but in some applications only natural products are acceptable because of their biodegradability and their lack of toxicity. As far as microbial polymers are concerned, xanthan has the largest share of the market. The non-food usage of polysaccharides directly reflects their various physical attributes. Before their use is contemplated, they must be fully evaluated against other possible synthetic and natural products. If these other products are cheaper, they may be preferred even though the microbial polysaccharide is superior in the application envisaged. They are more expensive than starch or than synthetic products such as polyacrylamides, so use of the exopolysaccharide may incur an unacceptable cost penalty. However, because of changes in prices and availability of plant and algal products, there is considerable opportunity for expansion of the industrial use of microbial polysaccharides, especially as new products with unique physical properties are discovered. The oil industry provides one major scenario in which exopolysaccharides have readily found acceptance for a number of purposes, in competition with plant gums and their derivatives and with synthetic chemicals. If the numerous proposed enhanced oil-recovery developments come to fruition, the use of xanthan and other microbial exopolysaccharides could well increase very significantly indeed. Other industrial applications have secured a wide range of technological uses for exopolysaccharides with different physical properties. Some of these are limited in scale and will require only small amounts of polymer, but others contribute significantly to the overall demand.