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I, BR 285, km 171, CP 611, Brasil Recebido em 26/8/12; aceito em 5/2/13; publicado na web em 15/4/13 PRODUCTION OF BIOSURFACTANTS BY MICRORGANISMS ISOLATED FROM SOIL CONTAMINATED WITH DIESEL OIL. The aim of this work was to produce biosurfactants through submerged fermentation using microorganisms isolated from soil contaminated with diesel. Microorganisms were isolated, characterized by the production of biosurfactants, and used to study the influence of type, induction and concentration of ammonium sulfate as a nitrogen source in the culture medium. The microorganisms that showed best results, in terms of production of biosurfactants, were identified as being of the genus Pseudomonas and Bacillus. The biosurfactants produced proved capable of reducing the surface tension of the media to 39 mN/m and 34 mN/m, respectively. Higher biosurfactant production was obtained in the medium containing 1% soybean oil without ammonium sulfate.

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Research on the influence of biosurfactants on the efficiency of in situ bioremediation of contaminated soil is continuously growing. Despite the constant progress in understanding the mechanisms involved in the effects of biosurfactants, there are still many factors that are not sufficiently elucidated. There is a lack of research on autochthonous or exogenous microbial metabolism when biostimulation or bioaugmentation is carried out to produce biosurfactants at contaminated sites. In addition, studies on the application of techniques that measure the biosurfactants produced in situ are needed. This is important because, although the positive influence of biosurfactants is often reported, there are also studies where no effect or negative effects have been observed. This review aimed to examine some studies on factors that can improve the production of biosurfactants in soils during in situ bioremediation. Moreover, this work reviews the methodologies that can be used for measuring the production of these biocomposts. We reviewed studies on the potential of biosurfactants to improve the bioremediation of hydrocarbons, as well as the limitations of methods for the production of these biomolecules by microorganisms in soil.