Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Arslanoğlu, AlperSubject: search.filters.subject.Lipase--Biotechnology

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  • Master Thesis
    Cloning and Expression of the Pseudomonas Ke38 Extra-Cellular Lipase Gene in E. Coli
    (Izmir Institute of Technology, 2013) Karakaş, Fulya; Arslanoğlu, Alper
    Lipases are serine hydrolases that catalyze both the hydrolysis and synthesis of insoluble or poorly soluble long-chain triacylglycerols with an acyl chain length ≥ 10 carbon atoms based on the presence or absence of water. Lipases are produced and secreted by all kingdoms of life that are eukaryotes including plants, animals, fungi and prokaryotes including bacteria and archaea. However, microbial lipases, especially from bacteria, more useful than their plant and animal derivatives because of several important properties. Because of their acitivities in both aqueous and nonaqueous environments, lipases have specific applications in industry and medicine. The primary goals of this thesis were to clone and express the extra-cellular lipase gene from Pseudomonas sp. KE38, isolated from soil samples of Erciyes mountain in Kayseri, in E. coli and partial purification of the gene product. To achieve this aim, genome walking technique was used to obtain lipase gene from Pseudomonas sp. KE38, that gene was then cloned into pET28a expression vector and expressed in E. coli. The lipase expression of E. coli BL21 and its activity was screened with olive oil-Rhodamin B plate assay. After expression recombinant lipase was partially purified via inclusion body isolation. Moreover the optimum lipase production time of E. coli BL21 cells were determined and analyzed with SDS-PAGE. According to SDS-PAGE analysis the recombinant lipase was approximately 64 kDa and lipase production reached to the highest level after two hours of IPTG induction. As conclusion, recombinant lipase from Pseudomonas sp. KE38 was cloned into E. coli, expressed and partially purified.
  • Master Thesis
    Isolation and Identification of Lipase Producing Soil Fungus; Cloning, Sequencing and Partial Characterization of Its Lipase
    (Izmir Institute of Technology, 2010) Ergülen, Elvan; Arslanoğlu, Alper
    Lipases are well known enzymes which catalyze the hydrolysis of long chain triglycerides. Contrary to many other enzymes, lipases show a wide range of substrate specificity and remarkable levels of activity and stability in non-aqueous environments. Therefore, they have a great potential in many industrial applications such as detergent industry, paper and food technology, as biocatalysts for the synthesis of organic intermediates. Lipases can be obtained from animals, plants as well as from natural and recombinant microorganisms in good yields. The aim of this thesis was isolation and identification of a lipolytic fungus and purification and characterization of its lipase enzyme. For this purpose, a lipolytic fungus was isolated from soil sample collected from Kula. Lipase activity of this fungus was detected rapidly by Rhodamin B - olive oil plate assay. The lipolytic fungus was identified by 28S rRNA gene sequence analysis and determined to be a strain of Rhizopus stolonifer. Because this lypolytic fungus was isolated from soil sample collected from Kula, it was named as R. stolonifer K45. This fungus showed best growth at 25°C and did not grow above 35°C. In the second part of the study, lipase enzyme of the fungus was partially purified but previously, optimum time and carbon source for lipase production was determined. According to this, optimum lipase production was obtained at 7th day of growth in the media including only olive oil as carbon source. Glucose when included in the growth media was observed to reduce the amount of lipase. In order to purify fungal lipase, aceton precipitation (30 %) and ultrafiltration methods were used. Lipase activity assay was performed spectrophotometrically. The chain length specificity of this lipase was detected and highest activity was observed towards p-NP laurate. The effect of different temperature and pH values on lipase activity and stability was also determined and optimum temperature and pH were found 45°C and pH 8, respectively. Furhermore, different organic solvents and metal ions were tested on lipase activity. The lypolytic enzyme was inhibited by n-hexane. However, methanol and DMSO were detected to enhance the lipase activity.