Effect of Growth Conditions on Biosurfactant Production by Pseudomonas balearica Isolated from Oil Contaminated Sea Waters from Jeddah Saudi Arabia

The biosurfactant produced by Pseudomonas balearica isolated from oil-contaminated sea water was studied in the present research. A range of different growth conditions, such as temperature, pH, incubation period, inoculum size and different carbon/nitrogen sources and different C/N ratios were investigated to determine the optimum conditions for maximum production of a biosurfactant by the selected bacterial strain using a mineral salt medium. The best carbon andnitrogen sources were olive oil and urea, giving biosurfactant yields of 6.23 +/- 0.06 and 6.33 +/- 0.10 mg/ml, respectively. The maximum rhamnolipid production was 6.40 +/- 0.14 mg/ml at C/N (olive oil/ urea) of 30. The highest biosurfactant yield was at pH 7 (6.37 +/- 0.06 mg/ml), with inoculum size 2% (6.29 +/- 0.16 mg/ml), and incubation temperature 30 degrees C (6.18 +/- 0.14 mg/ml) and after a 312 hrs incubation period (6.30 +/- 0.09). The previous investigated nutritional and environmental factors showed the highest emulsification activity. The produced rhamnolipid biosurfactant reduced the surface tension of water from 72 to 34 mN/m. In conclusion, the findings herein demonstrated that the rhamnolipid biosurfactant production by P. balearica can be used during oil hydrolysis.

Automated summary

This study investigated the biosurfactant produced by P. balearica isolated from oil-contaminated sea water to determine optimal production conditions. Olive oil and urea were found to be the best carbon and nitrogen sources, with pH 7, inoculum size 2%, incubation temperature 30℃, and 312 hours of incubation period yielding the highest biosurfactant production. The biosurfactant reduced water surface tension from 72 to 34 mN/m, demonstrating potential for use in oil hydrolysis.