Petroleum hydrocarbons such as crude oil are important environmental contaminants. This study aims to
isolate and identify bacterial strains from crude-oil contaminated environments with the capacity to produce
biosurfactants when grown on a hydrophobic phase as well as to degrade petroleum hydrocarbons.
Three strains were screened out using a combination of blood nutrient agar (NA) plate screening and
crude oil mineral salt medium (MSM) plate tests. Grown on waste frying oil, all three strains were shown
to produce rhamnolipids as biosurfactants. The three strains could also degrade n-alkanes up to n-C40.
The removal efficiency of crude oil of each strain after 7 days of aerobic cultivation ranged from 36.0%
to 46.4%, among which strain Z41 performed best. Gas chromatographic analysis of the residual oil
showed that the degradation characteristics of the three strains differed from each other. The three
strains behaved similarly in terms of glycolipid production as in crude oil degradation, suggesting biosurfactant
production played a vital role in petroleum degradation. Using morphological, biochemical and
physiological characterization and 16S rRNA sequencing, the three strains were identified as Pseudomonas
aeruginosa, however producing very little amounts of pyocyanin. In this study, an efficient and simple
protocol to screen out biosurfactant producing and crude oil degrading bacterial stains was developed.
The reason why P. aeruginosa is often employed as biosurfactant-producing or oil-degrading strain
may be found in its wide spread occurrence in contaminated environments, rapid growth, the ease of isolation
and screening as well as the high biosurfactant production and crude oil degradation capacity.
Petroleum hydrocarbons such as crude oil are important environmental contaminants. This study aims toisolate and identify bacterial strains from crude-oil contaminated environments with the capacity to producebiosurfactants when grown on a hydrophobic phase as well as to degrade petroleum hydrocarbons.Three strains were screened out using a combination of blood nutrient agar (NA) plate screening andcrude oil mineral salt medium (MSM) plate tests. Grown on waste frying oil, all three strains were shownto produce rhamnolipids as biosurfactants. The three strains could also degrade n-alkanes up to n-C40.The removal efficiency of crude oil of each strain after 7 days of aerobic cultivation ranged from 36.0%to 46.4%, among which strain Z41 performed best. Gas chromatographic analysis of the residual oilshowed that the degradation characteristics of the three strains differed from each other. The threestrains behaved similarly in terms of glycolipid production as in crude oil degradation, suggesting biosurfactantproduction played a vital role in petroleum degradation. Using morphological, biochemical andphysiological characterization and 16S rRNA sequencing, the three strains were identified as Pseudomonasaeruginosa, however producing very little amounts of pyocyanin. In this study, an efficient and simpleprotocol to screen out biosurfactant producing and crude oil degrading bacterial stains was developed.The reason why P. aeruginosa is often employed as biosurfactant-producing or oil-degrading strainmay be found in its wide spread occurrence in contaminated environments, rapid growth, the ease of isolationand screening as well as the high biosurfactant production and crude oil degradation capacity.
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