Abstract
Biosurfactants are a cleaning option for environments contaminated with oil. This compounds of microbiological origin have low toxicity. In pursuit of this biocompound, seawater samples were collected, diluted and striated in Petri dishes containing agar nutrient for bacterial growth. After bacteria isolation an screening was made to studied its potential. Subsequently, biosurfactant production by a bacterium isolated from seawater was performed by varying the carbon source (glucose, soybean oil and residual soybean oil frying) and nitrogen (sodium nitrate, potassium nitrate, urea and peptone). The identification of the isolates was made by mass spectrometry using Matrix-Assisted Laser Desorption Ionization – Time of Flight (MALDI- TOF). After selection of the media that showed best results, the biosurfactant produced by Bacillus sp. was studied from the best growing conditions, varying growth time (48, 72 and 96 hours) and the stirring speed (150, 200 and 250 rpm).The parameters evaluated were the determination of surface tension in mN/m and the concentration in g/L. The results showed that the medium containing potassium nitrate and frying oil at 200 rpm for 72 hours showed the best results. A surface tension of 29 mN/m and a concentration of 3.6 g/L were observed. Tests under extreme conditions of pH, temperature and NaCl indicated the stability of the biosurfactant for use in the treatment of oil-contaminated environments. Washing experiments involving soil contaminated with motor oil demonstrated recovery rates greater than 90 %. The crude biosurfactant was capable of dispersing approximately 74 % of oil droplets in seawater, demonstrating that the biosurfactant can be used in future removal tests of oily compounds in industrial processes.
