Comparative Study of Biosurfactant Synthesis by Pseudomonas aeruginosa isolated from Clinical and Environmental Samples.
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Evaluation of emulsifying activities indicates that biosurfactants were produced by an environmental (strain EPl) and a clinical (strain EPl) species of Pseudomonas aeruginosa. During growth on hydrocarbons, the organisms produced biosurfactants. Both strains grew luxuriantly on motor oil and readily synthesized abundant surfactants at the expense of easily metabolizable substrates. During a12 day cultivation on motor oil, the organisms produced growth associated extracellular surfactants with emulsification activities of 71 and 38% for EPl and CPl, respectively. The general times obtained for EPl and CPl were 1.74 and 2.66 days. The biosurfactants that could not be secreted on glucose were partially purified and putatively identified as rhamnolipids. The surface-active compounds present high emulsification activity and stability in the pH range of 3.0-10.0, temperature range of 4oC-100oC, and salinity range of 16 -44% and are capable of stabilizing oil-in-water emulsions with several hydrocarbons. Typical emulsions produced were stable for several weeks. The results also showed that the biosurfactants were able to remove a significant amount of crude oil from contaminated soil; for instance, strain EPl surfactant removed 54%, CPl 41%, detergent 42%, and water 30%. The rhamnolipids from these strains represent a new class of biosurfactants that have potential for use in a variety of biotechnological and industrial applications where extremes of pH, thermal, and saline conditions would have little or no effect on activity.
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Biosurfactants , Pseudomonas aeruginosa , Metabolizable substrates , Rhamnolipids
Comparative Study of Biosurfactant Synthesis by Pseudomonas aeruginosa isolated from Clinical and Environmental Samples. Petroleum Science and Technology 30: 1-15.