CONICET | Buscador de Institutos y Recursos Humanos

Hydrophobic compounds bioavailability is a key factor for their biodegradation and mobilization.Because of that, the use of surfactants was proposed as additives in Surfactant Enhanced Remediation(SER) and in Surfactant Enhanced Oil Recovery (SEOR). The use of biosurfactants instead of thesynthetic ones have some environmental advantages like less toxicity and higher biodegradability, thatmake these biomolecules an environmentally friendly alternative. Previous studies from our groupshowed that Pseudomonas sp. KA-08 was able to secrete biosurfactants to the culture media when itgrew in kerosene as sole carbon source and a crude extract surfactant (CES) could be obtained from acell-free supernatant of these cultures. In this work we analyzed the surface tension loweringcapabilities of the different compounds present in the CES and their chemical composition.Pseudomonas sp. KA-08 was cultured in 50 ml E2 minimum medium supplemented with 10% kerosenein 500 ml capped bottles at 280 rpm and 30°C. After 7 days, cultures were centrifuged at 3500 rpm for20 minutes, the oil phase was removed and supernatants were acidified up to pH 2 and left overnightat 4°C. Then, they were extracted thrice with half the volume of ethyl acetate and concentrated todryness by Rotavap to obtain the CES. To calculate its critical micelle concentration (CMC) a Du Nouyring method was used, obtaining a CMC = 670 μg/ml ± 76 μg/ml. For better characterization of theCES components, a silica gel chromatographic column (diameter: 1,50cm, length: 40cm) wasperformed using solvents in increasing order of polarity as elutants, in order to separate thecompounds for further analysis. The elution fractions were collected, analyzed by TLC and revealedwith UV light or Molisch reagent. The fractions who showed unique spots with a conserved Rf weregrouped, obtaining 4 pooled fractions. Each pool was evaporated to dryness, resuspended inbidistilled water and tested by the drop-collapse method. Three of them showed a contact angledismitution of 10° ± 3°, 18° ± 4° and 18° ± 3° respectively. The predominant one, who showed positivefor Molisch reagent ( glycosidic nature) was analyzed by 1H and 13C-NMR spectroscopy and exhibitedcomplex spectra with aliphatic and aromatic moieties.This work allows us to continue the chemical analysis of the compound purified and to study thepotential use of the CES as a biosurfactant additive in microcosms polluted with hydrocarbons.

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