Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Genotypic Characterization of Extracellular Enzyme Producing Thermophilic Bacteria in Balçova Geothermal Region(Izmir Institute of Technology, 2003) Yavuz, Elif; Yenidünya, Ali Fazıl; Yavuz, Elif; Yenidünya, Ali Fazıl; 04.03. Department of Molecular Biology and Genetics; 01. Izmir Institute of Technology; 04. Faculty of ScienceThermophiles are the organisms which are adapted to live at high temperatures. The enzymes from thermophiles find a number of commercial applications because of their thermostability and thermoactivity. Therefore, the isolation of thermophilic bacteria from natural sources and their identification are very important in terms of discovering new industrial enzymes.In keeping with this view, Balçova Geothermal Region could serve as a good source for new thermophilic microorganisms with novel industrially important properties.The aim of this research was therefore the isolation of industrially important extracellular enzyme producing thermophilic bacteria from Balçova Geothermal Region and their identification by genetical means. 16S-ITS rDNA RFLP, plasmid profiling and pulsed field gel electrophoresis studies were performed for this purpose.112 thermophilic strains were isolated from various environmental samples collected within Balçova Geothermal Region. These strains were screened for the existence of 6 extracellular enzyme activities. These were, lipases, amylases, proteases, xylanases, cellulases and pectinases. In total, 110 lipase (tween 20 as substrate), 106 amylase, 55 protease, 28 xylanase, 10 cellulase and 3 pectinase activities were detected.Some other phenotypic tests were also performed for these isolated strains. Since all the isolated strains were Gram (+), endospore forming rods, they were identified as Bacillus sp.16S-ITS rDNA RFLP and plasmid RFLP profiles were produced by using two restriction endonucleases Taq I and Hae III . The isolated strains were clustered into eleven groups by Taq I restriction profiles of 16S-ITS rDNA while nine groups were obtained by Hae III digestion profiles. When these groups were compared, it was concluded that 17 genotypically different strains existed in total 112 isolates. Two of the isolated strains yielded similar RFLP profiles to those of Bacillus stearothermophilus (CECT 43) reference strain.Plasmid profiling was also performed. It was found that 23 of the isolated strains contained plasmid DNA. Hae III restriction profiles indicated the existence of three different types of plasmids.PFGE optimization studies by Sma I restriction endonuclease for thermophilic Bacilli were also performed. A new method for preparation of agarose plugs was developed.Master Thesis Isolation and Molecular Characterization of Lactic Acid Bacteria From Raw Milk(Izmir Institute of Technology, 2002) Çetin, Ali Emrah; Yenidünya, Ali Fazıl; Yenidünya, Ali Fazıl; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of TechnologyLactic acid bacteria are industrially important because they are used as starter cultures in food production, they produce antimicrobial compounds and they are used in the formulation of probiotic products. Several dairy products such as raw milk, traditionally fermented cheese (produced without the use of commercial starter cultures), and kefir which are produced in country are good sources of novel lactic acid bacterial strains. These lactic acid bacterial strains may have potential for the production of new fermented dairy products with characteristic aroma and flavour. Therefore, the isolation of lactic acid bacteria from natural products and their identification are important. For many years, several phenotypic methods have been used to identify lactic acid bacteria, but they are not often capable of effectively differentiating subspecies and strains within a genus. New methods based on the genotypic properties have been developed and used for the proper classification of bacteria The aim of this research was the isolation of lactic acid bacteria from raw milk and the identification of the lactic acid bacterial isolates by biochemical tests, polymerase chain reaction (PCR)-based methods and pulsed field gel electrophoresis (PFGE). Lactic acid bacteria were isolated from cow.s raw milk and identified by biochemical reactions. Two PCR based methods, ITS-PCR (Internal Transcribed Spacer-PCR) and PCR-RFLP (PCR- Restriction Fragment Length Polymorphism) were then used for the differentiation of reference strains of lactic acid bacteria. PCR-RFLP method, based on the amplification and restriction digestion of 16S rRNA gene, was found to be useful for the identification. Thirteen raw milk isolates were identified as Lactococcus lactis, 24 as Enterococcus spp., and 2 as Lactococcus lactis subsp. cremoris by PCR-RFLP method. Pulsed field gel electrophoresis was also optimized for the identification of reference strains. Restriction profiles obtained by digesting the genomic DNA with Sma I enabled differentiation of the reference strains of Lactococcus, Enterococcus, and Streptococus thermophilus.