Trends in Biotechnology
Volume 24, Issue 11, November 2006, Pages 509-515
Journal home page for Trends in Biotechnology

Review
Towards commercial production of microbial surfactants

https://doi.org/10.1016/j.tibtech.2006.09.005Get rights and content

Biosurfactants or microbial surfactants are surface-active biomolecules that are produced by a variety of microorganisms. Biosurfactants have gained importance in the fields of enhanced oil recovery, environmental bioremediation, food processing and pharmaceuticals owing to their unique properties – higher biodegradability, lower toxicity, and effectiveness at extremes of temperature, pH and salinity. However, large-scale production of these molecules has not been realized because of low yields in production processes and high recovery and purification costs. This article describes some practical approaches that have been adopted to make the biosurfactant production process economically attractive: these include the use of cheaper raw materials, optimized and efficient bioprocesses and overproducing mutant and recombinant strains for obtaining maximum productivity. The application of these strategies in biosurfactant production processes, particularly those using hyper-producing recombinant strains in the optimally controlled environment of a bioreactor, might lead towards the successful commercial production of these valuable and versatile biomolecules in near future.

Section snippets

Microbial surfactants

Microbial surfactants are surface-active metabolites produced by microorganisms when grown on water miscible or oily substrates: they either remain adherent to microbial cell surfaces or are secreted in the culture broth. They possess the characteristic property of reducing the surface and interfacial tensions using the same mechanisms as chemical surfactants. Microbial surfactants constitute a diverse group of surface-active molecules and are known to occur in a variety of chemical structures,

Cheap substrates: economical and promising alternatives

Production economy is the major bottleneck in biosurfactant production, as is the case with most biotechnological processes. Often, the amount and type of a raw material can contribute considerably to the production cost; it is estimated that raw materials account for 10 to 30% of the total production costs in most biotechnological processes. Thus, to reduce this cost it is desirable to use low-cost raw materials [6]. One possibility explored extensively is the use of cheap and agro-based raw

Bioprocess development: optimum production and recovery

An efficient and economical bioprocess is the foundation for every profit-making biotechnology industry; hence, bioprocess development is the primary step towards commercialization of all biotechnological products, including biosurfactants. Any attempt to increase the yield of a biosurfactant demands optimal addition of media components and selection of the optimal culture conditions that will induce the maximum or the optimum productivity. Similarly, efficient downstream processing techniques

Mutant and recombinant strains: the hyperproducers

The genetics of the producer organism is an important factor affecting the yield of all biotechnological products because the capacity to produce a metabolite is bestowed by the genes of the organism. The bioindustrial production process is often dependent on the use of hyperproducing microbial strains: even with cheap raw materials, optimized medium and culture conditions, and efficient recovery processes, a production process cannot be made commercially viable and profitable until the yield

Concluding remarks

Successful commercialization of every biotechnological product depends largely on its bioprocess economics. At present, the prices of microbial surfactants are not competitive with those of the chemical surfactants due to their high production costs and low yields. Hence, they have not been commercialized extensively. However, the use of cheaper substrates and optimal growth and production conditions coupled with novel and efficient multistep downstream processing methods and the use of

Acknowledgements

SM acknowledges CSIR for his research fellowship, PD acknowledges IIT, Kharagpur for her institute scholarship and RS acknowledges the ISIRD grant from IIT, Kharagpur.

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