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|العنوان:||Growth and Biotransformation of Progesterone by Thermophilic Geobacillus gargensis and its Membrane Lipid Composition under Variable Abiotic Stress||المؤلفون:||نور عيسى البلوشي||Supervisor:||أ.د. محمد افضل||الموضوع:||Biotransformation Geobacillus gargensis Membrane Lipid Composition||تاريخ الاصدار:||2013||الناشر:||Kuwait university - college of graduate studies||ملخص:||Geobacillus gargensis growth conditions were optimized in minimal salt medium and its growth curve against different times was constructed. The bacterium was also cultured under different temperatures, salt concentrations, pH variation and under these conditions, growth curves were produced. The bacterium G. gargensis, was incubated with exogenous progesterone as a carbon source under different growth conditions. These conditions were optimized for progesterone metabolism under different abiotic stresses including temperature shock, pH, incubation time, and salinity. The bacterial cells were incubated (for 10 hr, pH 7, 86 mM NaCl, and at 60 oC) with progesterone as a sole source of carbon. The biotransformed progesterone products, formed under different stress conditions, were purified by thin layer chromatography and identified by use of several techniques including 1HNMR, 13CNMR, FTIR and mass spectrometry. Three monohydroxylated progesterone metabolites were identified: 20α-hydroxyprogesterone, 6α-hydroxyprogesterone, and 6β-hydroxyprogesterone. The 20α-hydroxyprogesterone is a rare metabolite of progesterone, which is characteristic of G. gargensis. To study alterations in the membrane lipids and their component fatty acids, the bacterial cells were cultured under differential abiotic stresses. The organism, in order to maintain appropriate membrane fluidity, altered its total lipids and the ratio of saturated/unsaturated; iso-/anteiso-fatty acids; branched/saturated straight chain FA under gradient pH, salt, anoxic conditions, incubation time and temperature stresses. The branched-chain fatty acids through their characteristic chemical properties supported the bacterial growth under nonoptimal growth conditions. v Under optimal growth conditions, G. gargensis constantly maintained iso-/anteiso-fatty acid ratio indicating the organism adaptability/resistance to the applied abiotic stresses. G. gargensis membrane phospholipid consisted of five main phospholipids: phosphatidylcholine, phosphatidylglycerol, cardiolipin, phosphatidylethanolamine, and phosphatidic acid. In addition, four unidentifiable phospholipids were detected in mixtures extracted from the bacterium cultured under different abiotic stress.||URI:||http://hdl.handle.net/123456789/197|
|يظهر في المحتويات:||0495 Microbiology|
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