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, possibility of large-scale production, selectivity, performance under extreme conditions and potential applications in environmental protection [1][2].
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 [3][4][5]. These compounds can also be used in enhanced oil recovery and may be considered for other potential applications in environmental protection [5][6]. Other applications include herbicides and pesticides formulations, detergents, health care and cosmetics, pulp and paper, coal, textiles, ceramic processing and food industries, uranium ore-processing and mechanical dewatering of peat [1][2][7].
Several microorganisms are known to synthesise surface-active agents, most of them are bacteria and yeasts [8][9]. 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 [10][11]. 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.
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References
- ^ a b Banat, I. M., Makkar, R. S., Cameotra, S. S.: Potential commercial applications of microbial surfactants. Appl. Microbiol. Biotechnol. 53 (2000), 495−508.
- ^ a b 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.
- ^ 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.
- ^ a b 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.
- ^ 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.
- ^ Ron, E. Z., Rosenberg, E.: Natural roles of biosurfactants. Environ. Microbiol. 3 (2001), 229−236.
- ^ 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.
- ^ 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.
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