2011 YÜksek lisans tez özetleri

Investıgatıon Of Sulfate-Reducıng Bacterıa In The Petroleum Samples Taken From The Oıl Fıelds Of Southeast Anatolıa Regıon

It is established that the most of diverse microbial populations possessing a range of different metabolic activities inhabit subterranean environments, including oilfield reservoirs. Because the redox potential of the production water is low and oxygen is generally absent, anaerobiosis is highly favored over aerobiosis in the reservoirs. In this respect, despite several aerobic microorganisms have been isolated from the oilfield environments, much attention has been paid to anaerobes such as sulfate-reducing bacteria (SRB), methanogens, fermentative microorganisms, nitrate, manganese and iron reducers. This is especially important for SRB which are known as being responsible for posing various problems during the oil production.

SRB generate hydrogen sulfide (H₂S), which is an acidic and a toxic product, using sulfate ions in the environment as terminal electron acceptor under anoxic conditions. Released H₂S causes corrosion of materials used in oil industry. Also, the toxic effect of H₂S produced in reservoirs poses a great danger in terms of health and safety of the workers. Moreover, it was determined that SRB utilize hydrocarbons in crude oil as a substrate severely and therefore reduce the quality of oil. Since they lead to economic losses and threat to human health, SRB have been regarded as unwanted microorganisms in petroleum.

The aim of this study is to determine the presence, the abundance and the ecology of SRB in 20 different production wells located in the Southeast Anatolia Region and to establish the species-level bacterial diversity in the oil samples taken from these wells.

In this study, number of SRB was determined in the oil phase and oil-water phase of the oil samples, morphology and spor formation was observed under the light and phase-contrast microscobes. H₂S concentration in the bacterial cultures was measured by Gas chromatography–mass spectrometry (GC-MS). In addition, diversity of bacterial species in the oil-water phase samples was identified by Polimerase Chain Reaction (PCR) and Denaturing Gradient Gel Electrophoresis (DGGE) methods.

It was determined that the number of SRB was generally low (<10 cells/ml) in the oil reservoirs and more growth of SRB was observed in the oil phase when compared to the oil-water phase. Both Gram-positive and Gram-negative bacteria with different morphologies were observed in the bacterial cultures including SRB. Despite being low SRB numbers, high H₂S concentrations were observed in the culture bottles. As a result of molecular analyses, uncultured bacteria (70 %) in the oil-water phase were mainly determined. Among the cultured bacteria, Proteobacteria (% 18), Actinobacteria (% 6), Bacteriodetes/Chlorobi (% 3) and Firmicutes (%3) groups were present.

  

EROL Zeynep

Danışman : Prof. Dr. Seyhan ALTUN

Anabilim Dalı : Biyoloji

Programı : Genel Biyoloji

Mezuniyet Yılı : 2011

Tez Savunma Jürisi : Prof. Dr. Seyhan ALTUN

Prof. Dr. Şehnaz BOLKENT

Doç. Dr. Ömür BULAN

Doç. Dr. Gül ÖZCAN ARICAN

Doç. Dr. Ali KARAGÖZ