Production of emulsifier by a strain of Pseudomonas aeruginosa (C1 LBPVMA-UFAL) using lubricant oil as main carbon source

Ana Maria Queijeiro López,Danielle Dos Santos Tavares Pereira,Amanda Lys Santos Silva

doi:10.4025/actascitechnol.v32i1.7548

Abstract

The intention of this work was to evaluate the growth of Pseudomonas aeruginosa (C1 LBPVMA-UFAL) on lubricant oil and verify the production of rhamnolipid biosurfactant. Tests in solid medium containing lubricant oil supplemented with different sources of nitrogen were used to evaluate the growth of P. aeruginosa. The growth medium used for production of rhamnolipid was (g L-1): yeast extract, 0.1; NaCl, 1.0; MgSO4, 0.2; MnSO4.H2O, 0.02; 0.5% lubricant oil (w v-1). The biosurfactant concentration was detected 24h after the inoculation, during the exponential phase, with the maximum value obtained up to 120h, although no drastic alteration of pH had been verified. The emulsifier activity was also first detected after 24h of incubation, with maximum production after 120h. The characterization of the produced biosurfactant was performed through thin layer chromatography, which showed the presence of two spots with Rf values equal to 0.71 and 0.5, revealed by reagents specific to rhamnolipids. These results suggested that two types of rhamnolipidic biosurfactant are produced by the strain of P. aeruginosa in limited conditions of nutrients, able to use lubricant oil as main carbon source. This bacterium, isolated from agro-industrial effluent, showed potential to bioremediation assays of contamination with petrol and his derivates.

Highlights

Petrol is a complex mixture of many compounds such as alkanes, aromatics, resins and asphaltenes, which could potentially be eliminated by microbial degradation (BARATHI; VASUDEVAN, 2001)
Sources was based on the results here obtained and on the observations reported by Guerra-Santos et al (1984), which demonstrated the influences of nitrogen source on biosurfactant production from P. aeruginosa DSM2659
*P. aeruginosa C1 – isolate from agro-industrial effluent, identified at the LBPMAUFAL. **Yeast extract (0.5%; w v-1) was chosen as the nitrogen source for the medium containing lubricant oil as the main source of carbon for growth and biosurfactant production

Summary

Introduction

Petrol is a complex mixture of many compounds such as alkanes, aromatics, resins and asphaltenes, which could potentially be eliminated by microbial degradation (BARATHI; VASUDEVAN, 2001). Bacteria have adapted themselves to feeding on water-immiscible materials by manufacturing and using a surface active product that helps them in the aqueous phase. 33-36, 2010 adsorb, emulsify and disperse or solubilize the water immiscible material (HEALY et al, 1996). The use of synthetic surfactants in treating hydrocarbon systems contaminating soil improves the restoration of these areas, increasing the surface for microbial attack. They may promote accumulation in the ecosystem causing serious environmental damage (CUNHA; LEITE, 2000). The rate of hydrocarbon biodegradation is dependant of the biosurfactant effect, in two ways: by increasing solubilization and dispersion of the hydrocarbon, and by changing the affinity between microbial cells and hydrocarbons, by inducing increases in cell surface hydrophobicity (ZHANG; MILLER, 1995)

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