الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
 |  | from | 71 |  |  |
| | | from | 71 | | |
Abstract
The demand for new chemicals to be used in environment, agriculture, food and pharmaceutical sectors are steadily increasing. Generally, these chemicals must be both effective and environmentally compatible(1). Microbes produce a largely unexplored variety of chemicals such as biosurfactants. Biosurfactants (Biological Surface Active Agents) are amphiphlic in nature. They contain polar and non polar moieties. They have the ability to accumulate at interfaces and mediate between phases of different polarity that leads to lower both surface and interfacial tension Many microorganisms produce variety of biosurfactants.
Unlike chemically synthesized surfactants, biosurfactants can be classified according to their chemical composition and their microbial origin. Accordingly, biosurfactants can be classified to glycolipids, lipopeptides, lipoproteins, (phospholipids and fatty acids), particulate biosurfactants and polymeric biosurfactants. Biosurfactants have gained attention since they exhibit some advantages over that of chemically synthesized counterpart. They are biodegradable, have low toxicity, ecological acceptability and ability to be produced from cheaper substrates(3). It was reported that, microbial surfactants exhibit high specificity consequently they are suited to new applications (2, 4). Biosurfactants play roles in some environmental applications including the removal of heavy metals, organic compounds from soil and water and the bioremediation of hydrophobic compounds(2’4’5).
Surfactin, one of the most effective biosurfactants known so far, is a cyclic lipopeptide, most commonly produced by Bacillus members. Surfactin at a concentration of 0.005% (w/v) is capable to lower surface tension from 72 to 27.9 mN/m. A wide range of biotechnological, pharmaceutical and environmental applications utilizing Surfactin have been reported.
The present study aims at isolation of biosurfactants-producing bacterial isolates from different environmental samples petroleum oil waste, sea water with oil spills and petroleum oil contaminated soil. The aim is extended to identify the isolated bacterial isolates and to extract, purify and partially characterize the produced biosurfactants. Moreover, optimization of biosurfactant production through one variable at a time (OVAT), Plackett-Burman and RSM technique is conside