Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Investıgatıon of Desulfovıbrıo Sp. by FluorescenceıIn Sıtu Hybrıdızatıon (Fısh)

Method ın Petroleum Reservoırs ın Turkey South East Anatolıa Regıon
Oil fields harbor subsurface microbial communities that contain a rich diversity of bacteria. Redox potential of production water which is used for oil drilling is low, therefore anaerobic bacteria such as methanogens, nitrate, iron, manganese and sulphate reducing bacteria (SRB) are highly favored over aerobic bacteria in the reservoirs. Especially, SRB are known as being responsible for various problems at the oil industry while reducing sulfur compounds from SO₄^-2, SO₃^-2, S₂O₃^-2 to H₂S with dissimilative way. Desulfovibrio is the most frequently isolated genus of SRB from oil-water phase.
Desulfovibrio spp. generates H₂S gas which reduced the oil quality while souring the petroleum. It also causes microbiological influenced corrosion of metal equipments used in oil industry while oil drilling. Also, the toxic effect of H₂S produced in reservoirs is the result of a serious danger in terms of health and safety of both the workers and people who lives around the oil fields.
The most of the information about the diversity of SRB in nature and industrial systems are obtained via target genes. In molecular studies, 16S rRNA is used as target gene in order to obtain accurate and reliable results. FISH method enables the quick and safe detection of microorganisms living in different ecologies by using 16S rRNA probes. FISH analysis can be carried out in two different ways, such as membrane filter and teflon-coated slide technique.
The aim of this study is to determine the presence and the abundance of Desulfovibrio spp. in 11 oil and 5 waste water samples taken from 11 different oil wells located in the Southeast Anatolia Region (Batman and Diyarbakır) and also to specify bacterial diversity of Desulfovibrio spp. in the total bacterial population in the samples taken from these wells using both method of FISH technique and to determine whether there is any difference between the two methods in terms of results. In this study, probe SRB-687 labeled with Cy3 fluorescent dye was used for Desulfovibrio spp. and DAPI fluorescent staining technique was applied for the determination of total bacterial population.
According to the results of the membrane filter method from oil field samples in Diyarbakır and Batman Regions, the density of total bacteria of B5 well was determined 65654535 ± 21645659 cell/ml as the highest and D7 well was determined 20616158 ± 12587360 cell/ml as the lowest result. According to the teflon-coated slide technique density of total bacteria of D2 well was determined 27689086 ± 4796023 cell/ml as the highest and D8 well was determined 8880806 ± 3115394 cell/ml as the lowest result.
Desulfovibrio spp. was determined from all of the studied oil wells in Diyarbakır and Batman Regions. According to the membrane filter method, Desulfovibrio spp. was detected the highest number in B5 well as 28545450 ± 12765913 cell/ml and the lowest number in D2, D5 and D7 wells as 8155842 ± 7629092 cell/ml. Additionaly, according to the teflon-coated slide technique Desulfovibrio spp. was detected the highest number in D4 well as 11744413 ± 5343996 cell/ml and the lowest number in D8 well as 1903030 ± 932290 cell/ml.
According to the membrane filter method, Desulfovibrio spp. was determined 38.67 % of total bacterial population in terms of all wells in Diyarbakır while the rate was 43.18 % in Batman. However, Desulfovibrio spp. was determined as 35.75 % of total bacterial population in terms of all wells in Diyarbakır while the rate was determined 36 % in Batman by teflon-coated slide technique.
Result of the study in terms of the correlation between two different methods were showed that, the number of bacteria which was obtained by polycarbonate membrane filter was more higher correlated than teflon-coated slide technique results (p ≤ 0.05).
Desulfovibrio spp. was observed high number and abundant in both Diyarbakır and Batman Regions. These bacteria, which reduce the quality of petroleum and cause for microbiological influenced corrosion, have to be controlled and taken care of it.