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Title: Hydrocarbon Utilization by Microorganisms under Halostress
Authors: Maiss Abdulhadi Abdulmahdi Marafie 
Supervisor: Dr. Dina Musaed Al-Mailem
Keywords: Hydrocarbon Microorganisms Halostress
Issue Date: 2012
Publisher:  Kuwait university - college of graduate studies
Abstract: The major objective of this thesis was to answer the question as to whether hypersaline environments may accommodate halophilic/halotolerant microorganisms with hydrocarbon-utilization potential which may play a role in bioremediating oil-polluted hypersaline environments. Pond water and soil samples as well as samples of rhizospheres and phyllospheres of the halophyte Halocnemum strobilaceum from the southern Al-Sabkhah hypersaline area of Kuwait harbored oil-utilizing microorganisms in the magnitude of 103 to 104 colony forming units g-1 sample, as determined by the plating method. Highest numbers were counted on media containing 1 to 2 M NaCl (1 M = 5.8 %), but still considerable numbers were counted on media containing 3 and 4 M NaCl. Fifteen different bacterial, two different archaeal and one yeast species were isolated from the four habitats. They were characterized by sequencing their 16S rRNA coding genes. The individual isolates could grow on individual short-chain, medium chain, long-chain and very-long-chain n alkanes and the aromatics, phenanthrene, naphthalene and biphenyl as sole sources of carbon and energy in the presence of 1 M NaCl. Quantitative gas liquid chromatography determinations showed that all pure isolates could attenuate crude oil, pure n-octadecane (an alkane) and pure phenanthrene (an aromatic) in batch cultures containing 1 M NaCl. Also fresh environmental samples (with their inhabitant microorganisms), when used as inocula attenuated crude oil effectively in the presence of up to 4 M NaCl. Many of the pure isolates could grow in the media in which nitrogenous compounds had been deleted, indicating their probable diazotrophic potential. Hydrocarbon attenuation by pure isolates iii and whole microbial consortia in the environmental samples occurred optimally in the presence of 2 M NaCl, yet substantial activity was still maintained in the presence of up to 4 M NaCl. Molecular Fingerprinting by denaturing gradient gel electrophoresis showed that the amplified total DNA of environmental samples produced up to 16 DNA bands on the gel. It was concluded that the hypersaline environment studied harbored rather high numbers of oil-utilizing species belonging to bacteria, archaea and yeasts, several of which could probably be diazotrophic, these consortia appear to be effective in bioremediating oil in these hypersaline environments.
Appears in Programs:0520 Microbiology (M.Sc.)

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