Pure & Appl. Chern., Vol. 64, No. 11, pp. 1731-1737,1992, Printed in Great Britain. @ 1992 IUPAC
Biosurfactants in industry
Department of Chemical and Biochemical Engineering University of Western Ontario, London, Ontario, Canada, N6A 5B9
Biosurfactants (Microbial Surface Active Agents) have become recently an important product of biotechnology for industrial and medical applications. Thereason for their popularity, as high value microbial products, is primarily in their specific action, low toxicity, relative ease of preparation and widespread applicaility. They can be used as emulsifiers, de-emulsifiers, wetting agents, spreading agents, foaming agents, functional food ingredients and detergents in various industrial sectors such as . Petroleum and Petrochemicals, Organic Chemicals, Foods and Beverages, Cosmetics and Pharmaceuticals, Mining and Metallurgy, Agrochemicals and Fertilizers, Environmental Control and Management, and many others. INTRODUCTION
The unique properties of biosurfactants allow their use and possible replacement of chemically synthesized surfactants in a great number of industrial operations. Surfactants are used by many industries and one could easily say that there is almost no modern industrial operation where properties of surfaces and surface active agents are not exploited. The potential application of biosurfactants in industries is also a reality. There are many advantages of biosurfactants as compared to their chemically synthesized counterparts. Some of those are: Biodegradability. Generally low toxicity. Biocompatability and digestibility, which allows their application in cosmetics, pharmaceuticals and as functional food additives. Availability of raw materials. Biosurfactants can be produced from cheap raw materials which are available in large quantities. The carbon source may come from hydrocarbons, carbohydrates and/or lipids, which may be used separately or in combination with each other. Acceptable production economics. Depending,on the application, biosurfactants can also be produced from industrial wastes and byproducts and this is of particular interest for bulk production (e.g. for use in petroleum related technologies). Use in environmental control. Biosurfactants can be efficiently used in handling industrial emulsions, control of oil spills, biodegradation and detoxification of industrial effluents and in bioremediation of contaminated soil. Specificity. Biosurfactants, being complex organic molecules with specific functional groups, are often specific in their action. This would be of particular interest in detoxification of specific pollutants, de-emulsification of industrial emulsions, specific cosmetic, pharmaceutical and food applications. Concerning disadvantages, one of the problems is related to large scale and cheap production of biosurfactants. Large quantities are particularly needed in petroleum and environmental applications, which, due to the bulk use, may be expensive. To overcome this problem, processes should be coupled to utilization of waste substrates combating at the same time their polluting effect, which balances the overall costs. 1731
Another problem may be encountered in obtaining pure substances which is of particular importance in pharmaceutical, food and cosmetic applications. Downstream processing of diluted broths may be quite involved requiring multiple consecutive steps. Therefore, high yields and biosurfactant concentrations in bioreactors are essential for their facilitated recovery and purification. Most of the biosurfactants are high molecular weight lipid complexes which are normally produced under highly aerobic conditions. This is achievable in their ex-situ production in aerated bioreactors. When their large scale application in petroleum and soil is encountered, their in-situ production (and action) would be advantageous. Low oxygen availability under these conditions requires...
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