Biosurfactant

Biosurfactants are surface-active substances synthesised by living cells. They have the properties of reducing surface tension, stabilising emulsions, promoting foaming and are generally non-toxic and biodegradable. Interest in microbial surfactants has been steadily increasing in recent years due to their diversity, environmentally friendly nature, possibilityof large-scale production, selectivity, performance under extreme conditions and potential applications in environmental protection Banat, I. M., Makkar, R. S., Cameotra, S. S.: Potential commercial applications of microbial surfactants. Appl. Microbiol. Biotechnol. 53 (2000), 495−508.] Rahman, K. S. M., Thahira-Rahman, J., McClean, S., Marchant, R., Banat, I.M.: Rhamnolipid biosurfactants production by strains of Pseudomonas aeruginosa using low cost raw materials. Biotechnol Prog. 18 (2002), 1277−1281.] .

Biosurfactants enhance the emulsification of hydrocarbons, have the potential to solubilise hydrocarbon contaminants and increase their availability for microbial degradation. The use of chemicals for the treatment of a hydrocarbon polluted site may contaminate the environment with their by-products, whereas biological treatment may efficiently destroy pollutants, while being biodegradable themselves. Hence, biosurfactant producing microorganisms may play an important role in the accelerated bioremediation of hydrocarbon contaminated sites [Rosenberg, E., Ron, E. Z.: High and low molecular mass microbial surfactants. Appl. Microbiol. Biotechnol. 52 (1999), 154−162.] [Del ‘Arco, J. P., De Franca, F. P.: Influence of oil contamination levels on hydrocarbon biodegradation in sandy sediments. Environ. Pollut. 110 (2001), 515−519.] Rahman, K. S. M., Banat, I.M., Thahira-Rahman, J., Thayumanavan, T., Lakshmanaperumalsamy, P.: Bioremediation of gasoline contaminated soil by a bacterial consortium amended with poultry litter, coir pith and rhamnolipid biosurfactant. Bioresource Technol. 81 (2002), 25−32.] . These compounds can also be used in enhanced oil recovery and may be considered for other potential applications in environmental protection [Shulga, A., Karpenko, E., Vildanova-Martsishin, R., Turovsky, A., Soltys, M.: Biosurfactant enhanced remediation of oil-contaminated environments. Adsorpt. Sci. Technol. 18 (1999), 171−176.] . Other applications include herbicides andpesticides formulations, detergents, health care and cosmetics, pulp and paper, coal, textiles, ceramic processing and food industries, uranium ore-processing and mechanical dewatering of peat [Ron, E. Z., Rosenberg, E.: Natural roles of biosurfactants. Environ. Microbiol. 3 (2001), 229−236.] .

Several microorganisms are known to synthesise surface-active agents, most of them are bacteria and yeasts [Banat, I. M.: Biosurfactants production and possible uses in microbial enhanced oil recovery and oil pollution remediation: a review. Bioresource Technol. 51 (1995), 1−12.] [Kim, S.E., Lim, E. J., Lee, S.O., Lee , J. D., Lee, T.H.: Purification and characterisation of biosurfactants from Nocardia sp. L-417. Biotechnol. Appl. Biochem. 31 (2000), 249−253.] . When grown on hydrocarbon substrate as the carbon source, these microorganisms synthesise a wide range of chemicals with surface activity, such as glycolipid, phospholipid and others [Muriel, J.M., Bruque, J.M., Olias, J.M., Sanchez, A. J.: Production of biosurfactants by Cladosporium resinae. Biotechnol. Lett. 18 (1996), 235−240.] [Desai, J.D., Banat, I.M.: Microbial production of surfactants and their commercial potential. Microbiol. Mol. Biol. Rev. 61 (1997), 47−64.] . These chemicals are apparently synthesised to emulsify the hydrocarbon substrate and facilitate its transport into the cells. In some bacterial species such as "Pseudomonas aeruginosa", biosurfactants are also involved in a group motility behavior called swarming motility.

External links

* [http://www.ansijournals.com/biotech/2008/360-370.pdf Review of a Biosurfactant]
* [http://www.tees.ac.uk/schools/sst/research_biotechnology.cfm Biosurfactant Research Facilities in University of Teesside]

References