Isolation and Characterization of Biosurfactant-and Bioemulsifier-Producing Bacteria from Petroleum Contaminated Sites in Western Canada

摘要

Biosurfactant-producing bacteria were isolated from two petroleum contaminated sites in western Canada. Seven potential biosurfactant/bioemulsifier-producing isolates were screened and characterized. All of the seven isolates were able to form emulsions. Emulsion-stabilizing capacity was also measured up to 48 hrs. Strain C-111-2 and C-203-2 would lead to highly reduced surface tension. For strain C-203-2, the optimum conditions that supported bacteria growth and production were investigated. The influences of carbon sources, medium pH values, and temperature were taken into account. The experimental results indicated that the crude oil and glucose were promising carbon sources for biosurfactants production; the isolated strains produced a maximum concentration of biosurfactant in a neutral pH environment and showed a higher surface activity under the temperature level of 35 degrees C than that under 10 degrees C. To further optimize the carbon and nitrogen source for biosurfactant production, response surface methodology (RSM) was applied to explore the favorable concentration of two carbon sources: glucose, crude oil, and one nitrogen source, NaNO3. The optimal concentration of 8.1g/L, 4% and 3.9 g/L for glucose, crude oil, and NaNO3, respectively, which can be obtained through RSM analysis.