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Abstract

Cyanobacterial mats have been observed to inhabit polluted sites and to develop remarkably well after oil spill incidents. Such mats covered large areas of the coasts of Kuwait and Saudi Arabia short after the Gulf War oil spills in 1991 and the mats-covered sites showed more recovery than those uncovered. This observation opened a new horizon of utlizing mat-indigenous microorganisms for bioremediation purposes. Using molecular tools such as dentauring gradient gel electrophoresis (DGGE) and O2, pH and H2S microsensors, the diversity and activity of microorganisms were investigated under in situ oil pollution conditions. Degradation of oil derivatives by cyanobacterial mats was shown to be performed by microorganisms other than those normally obtained in cultures. Oil pollution was found to stimulate aerobic respiration and sulfate reduction in mats but inhibited photosynthesis. Mat samples from Saudi Arabia were rich in halophilic and thermophilic bacteria that degraded pristane and n-octadecane at salinities between 5 and 12% (w/v NaCl) and phenanthrene and dibenzothiophene at salinities between 3.5 and 8%. The same compounds were degraded at temperatures up to 45�°C. Biodegradation experiments demonstrated that aerobic heterotrophic bacteria, and not the cyanobacteria, to which they were always associated were the chief oil degraders in mats. However, the presence of cyanobacteria stimulated oil degradation by providing oil degraders with the necessary oxygen, fixed nitrogen and simple organics. We conclude that cyanobacterial mats contain consortia that are useful for bioremediation not only because of their richness in indigenous halophilic and thermophilic oil-degrading bacteria but also because of the continuous supply of limited nutrients by the cyanobacteria. The use of cyanobacterial consortia for bioremediation will circumvent the costly use of organic and inorganic fertilizers and their maintenance at large scale can take an advantage of the year-round availability of sunlight in the region.

Biography

Dr. Raeid M. M. Abed is an assistant professor at Sultan Qaboos University (SQU), Oman since September 2007. He completed his Ph.D. from the Max-Planck Institute for Marine Microbiology (MPIMM) in Bremen-Germany in 2001. After his PhD, he worked for 6 years at MPIMM as a research associate on different topics using state-of-art molecular and microsensor techniques to link the diversity of microorganisms to their function under in situ conditions. He published around 33 scientific papers in reputed peer-reviewed journals and 7 book chapters. Dr. Abed participated in 7 international scientific projects, supervised and cosupervised around 6 PhD and 16 master students and serves as a reviewer for several international journals.