Master Degree / Yüksek Lisans Tezleri

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

Browse

Filters

2004 - 200942010 - 20122

Settings

Author: search.filters.author.Tarı, CananLanguage: search.filters.language.en

Search Results

Now showing 1 - 6 of 6
  • Master Thesis
    The Confirmation of the Commercial Kits Used in the Detection of Antibiotics in Milk With Hplc (high Pressure Liquid Chromatography)
    (Izmir Institute of Technology, 2008) Alkan, Pınar; Tarı, Canan
    In this study, Charm II Assay was confirmed by HPLC for B-lactam, sulphonamide and tetracycline residues in milk. These antibiotics were chosen because they are most frequently used veterinary drugs and their detection have importance for milk quality and consumer's health. The results for confirmation of Charm II Assay showed that the test was very sensitive to all groups that were investigated and showed %100 true results for blank samples and spiked samples that were fortified with mixed standards at MRL (maximum residue limit) for each group. Average recoveries of HPLC used for confirmation were between 47% to 97% for beta-lactams, 61.5% to 84.8% for tetracyclines and 50.4% to 54.6% for sulphonamides. The results of analysis with the naturally contaminated milk samples showed that Charm II Assay may give false positive results. But this might be because of the high sensitivity of the test that sometimes HPLC may not reach that detection limit of Charm II assay or the milk samples may contain other compounds of investigated antibiotics that HPLC method can not detect.In samples that were collected for B-lactam determination, only 2 out of 81 samples were detected above MRL where the amounts were 6.5 ppb penicilin-G and 23.8 ppb ampicillin. The MRL for these B-lactam antibiotics are specified as 4 ppb by European Union regulations. The samples investigated for tetracycline residues which were found as positive and confirmed by HPLC were below MRL or negative. In samples investigated for sulphonamides only one sample out of 44 was above MRL where the amount was 119 ppb sulfamethazine.Analysis with 5 commercial milk samples showed none antibiotic residues. Only 4 samples out of 5 for sulphonamides were screened positive but after confirmation no residues were detected in these samples.
  • Master Thesis
    Effect of the Morphology of Aspergillus Sojae on Pectinase Enzyme and the Optimization of Fermentation Conditions
    (Izmir Institute of Technology, 2006) Göğüş, Nihan; Tarı, Canan
    The control of the morphology of fungi needs great attention for the optimal potential production of the product. For this purpose Aspergillus sojae ATCC 20235, which has no available literature report on the pectinase production, is used as a model in the determination of the optimum regions for maximum polygalacturonase synthesis and biomass formation with desired pellet morphology by using low cost carbon and nitrogen sources. Firstly, a full factorial statistical design, with the factors of, two taxonomically different strains, seven types of seed culture formulations (slants) and two types of fermentation media were used to investigate the effect of these parameters on the polygalacturonase (PG) production. According to statistical analysis, factors of strain types and fermentation media and the interaction between them were found significant on the enzyme activity. Aspergillus sojae in a complex media, inoculated with a seed culture prepared from molasses resulted in maximum PG activity (0.2 U/ml). Then, a two step optimization procedure with four factors (concentrations of maltrin and corn steep liquor (CSL), agitation speed and inoculation ratio) was used to investigate the effect of these parameters on the PG activity, mycelia growth (biomass) and morphology (pellet size) of Aspergillus sojae. According to the results of response surface methodology (RSM), concentrations of maltrin, CSL and agitation speed were significant (p<0.05) on both PG synthesis and biomass formation. As a result, maximum PG activity (13.5 U/ml) was achievable at high maltrin (120 g/l), low CSL (0 g/l), high agitation speed (350 rpm) and high inoculation ratio (2x107 total spore). The diameter of pellets ranged between 0.05-0.63 cm. The second optimization step improved the PG activity by 74 % and the biomass by 40 %. Furthermore characterization of the enzyme with respect to its optimum pH and temperature and the effect of these on the stability were considered. Determination of the thermal inactivation constant with its inactivation energy and the substrate specificity constant were estimated.
  • Master Thesis
    Bioethanol Production From Fungal Sources Using Low-Cost Agro-Industrial Waste Products
    (Izmir Institute of Technology, 2012) Evcan, Ezgi; Tarı, Canan; Özen, Fatma Banu
    In recent years, the rapid increase in environmental problems, greenhouse gas emissions, fuel prices and the unlimited consumption of fuel stocks made people search for some alternative energy sources. Bioethanol is one of the most popular alternative sources with its many beneficial features. Considering the sugar content of fruit pomaces, which are the waste of fruit juice industry, are very convenient and cheap fermentation raw materials for production of bioethanol. The aim of this study was to create a renewable alternative for fossil fuel and to provide a viable solution to multiple environmental problems simultaneously creating a sink for waste utilization and optimize bioethanol production from apple pomace hydrolysate using Trichoderma harzianum, Aspergillus sojae and Saccharomyces cerevisiae by statistical methods. Here, screening and optimization steps were conducted in order to determine the significant factors and their optimum levels. Factors such as inoculation rate of A.sojae and T.harzianum and agitation speed were considered as factor variables, whereas the response variable was bioethanol production. According to the results of the screening process, inoculation rate of S.cerevisiae was fixed as 4% and aeration method as vented. In the optimization step, levels of the other factors were enlarged. The highest bioethanol production and yield on substrate were 8.748 g/l and 0.946, respectively. Higher concentrations of inoculation rates of T.harzianum and A.sojae (6%) and agitation speed of 200 rpm led to maximum bioethanol production. Furthermore, the results pointed out that using cocultures because of its synergistic interactions is an effective way for production of bioethanol.
  • Master Thesis
    Transformation of Aspergillus Sojae With Vitreoscilla Hemoglobin Gene
    (Izmir Institute of Technology, 2010) Bardakçı, Betül; Tarı, Canan; Tari, Canan
    Aspergillus sojae known as koji mold is a non-aflatoxigenic fungus, designated with a GRAS status by FDA. This study considers the transformation of A. sojae with Vitreoscilla hemoglobin gene. Vitreoscilla hemoglobin is the bacterial hemoglobin, which enhances the oxygen transfer under microaerophilic conditions. Since industrial fungal fermentation with the high demand for oxygen are accounted to face oxygen limitations during the production of value added products like enzymes, antibiotics and organic acids; oxygen supply becomes an enormous problem to be solved by the manufacturers. To overcome this problem, an alternative solution using the vgb gene of Vitreoscilla and recombinant DNA technology and taking the A. sojae organism as model organism was proposed. The product of interest in this study was the exopolygalacturonase enzyme known to have wide applications in food, pharmaceutical, textile and paper industries. Here vgb gene was tried to be introduced to A .sojae via both protoplasting and electroporation methods. For transformation process vgb gene was cloned initially into plasmid ANIp4. For the selection of transformed A. sojae cells, uridine auxotrophic mutants were tried to be selected after UV mutagenesis. However, using a procedure based on selection of uridine supported growth did not result in A. sojae pyrG mutants. The success of transformation was initially observed by means of PCR analysis and agarose gel electrophoresis, later this was try to be confirmed by sequence analysis and agarose gel electrophoresis. However, due to the contamination problems accounted in the procedures the transformation with both methods could not be assured.
  • Master Thesis
    Studies on Alkaline Protease Production From Bacillus Sp.
    (Izmir Institute of Technology, 2004) Gençkal, Hande; Tarı, Canan
    The aim of this study was optimization of the conditions for the production of alkaline protease from the Bacillus strains coded as L18, L21 and I18, which were isolated from our natural habitats. Additionally, the goal was also to optimize the production of alkaline protease from Bacillus sp. L21 in a new low-cost media formulation by employing design of experiments and response surface methodology. Lastly, the focus was given to the determination of the characteristic properties of the crude alkaline protease of Bacillus sp. L21. The strains L21 and L18 were supplied by İYTE Department of Biology, whereas I18 was supplied by Ege University Department of Biology. These potential alkaline protease producer strains identified as Bacillus sp. were isolated from the products of a leather factory (strains L21 and L18) and from the soil of the Ege University Campus (strain I18). When the effects of environmental conditions on alkaline protease production from strains L21, L18 and I18 were studied, the optimum temperatures were determined as 30 C for strain I18 and 37 C for the strains L18 and L21. Similarly the optimum agitation speeds were 100 rpm for I18 and 180 rpm for L18 and L21. The optimum inoculation ratio was determined as 5% (v/v) for all three strains. The optimum incubation time was determined as 96 hours for the strains I18 and L21 and 125 hours for L18. The optimum initial media pH was estimated as pH 10 for strain L18 and L21. The relative importance of these factors on alkaline protease production was investigated by using a resolution IV fractional factorial design with single replicate of treatment combinations of four factors (soybean meal, corn steep liquor, CaCl2, Tween 80). Soybean meal, maltose, Tween 80 concentrations and initial pH were found to significantly influence the alkaline protease production. For obtaining the mutual interaction between the variables and optimizing these variables, Box-Behnken design and central composite design (CCD) using response surface methodology was employed. The neutral pH values of the medium and Tween 80 around its maximum level has a positive effect on proteolytic activity. Additionally, 4 sets of validation experiments were employed. The validation experiment, which state soybean meal, maltose, Tween 80 and pH as 2.5 g/L, 15 g/L, 0.35 g/L and 8.5, respectively, yielded an actual protease activity of 294.3 U/mL, where the model estimated a value of 338 U/mL. The Box-Behnken design and validation experiments were not sufficient to determine the true optimum values for the significant factors because of the saddle nature of the response surfaces. Therefore pH and Tween 80 were kept constant and a central composite design with two factors (soybean meal and maltose concentrations) was conducted. The adjusted R2 of the model was 93.3% with an insignificant lack of fit (p value.0.141). The CCD was able to determine the optimum value of soybean meal as 3.0 g/L, however it could be determined for maltose concentration after a set of additional experiments. Consequently, the optimum values of the four factors were determined as 8.0 for pH, 0.35 g/L for Tween 80, 3.0 g/L for soybean meal and 30-40 g/L for maltose concentration. The maximum activity under these conditions was 269.2 U/mL. In the characterization part of this study, the crude alkaline protease of Bacillus sp. L21 displayed a pH optimum of 11.0 and retained about 73-78% of its original activity between pH 4.0 and 11.0 in the stability studies. The optimum temperature for protease activity was found to be 60C and retained about 90% of the original activity even at 80C. By analyzing the thermal stability, the alkaline protease was found to be stable in a temperature range of 30C to 50C but lost about 30% of its activity at 60C after 30 min and 1 hour incubations both in the presence and absence of Ca2+-The protease from strain L21 showed high stability against both 5% and 15% (v/v) concentrations of H2O2 which is a bleaching agent, and retained approximately 82% and 94% of its activity, respectively, therefore, the present alkaline protease is thought to be a bleach-stable enzyme, so that it can be used in detergent formulations. There was no inhibitory effect observed from EDTA that further show that the enzyme is not a metalloprotease. However, PMSF (phenylmethylsulphonyl fluoride) strongly inhibited the protease activity, suggesting that the enzyme is a serine protease. In addition,CaC12 showed inhibitory effect on the enzyme, decreasing the activity to 90% of the control and this can be explained that the enzyme do not require the presence of Ca2+ ions to be active and stable.
  • Master Thesis
    Production of Pectinase Enzyme From Aspergillus Sojae Batch and Fed-Batch Systems
    (Izmir Institute of Technology, 2008) Doğan, Nergiz; Tarı, Canan
    Commercial preparations of pectinases derived from fungi are well known to have high biotechnological value in the industry. For this purpose, polymethylgalacturonase (PMG) and polygalacturonase (PG) were produced with high productivities by Aspergillus sojae ATCC 20235 by using low cost carbon (Maltrin) and nitrogen (Corn Steep Liquor, CSL) sources. There is no literature report to best of our knowledge on the fed-batch production, purification and characterization of polygalacturonase using this microorganism.In this study batch fermentation was carried out in order to obtain the crude PG and to establish a baseline for the forth coming fed-batch experiments. The crude PG was partially purified using three-phase partitioning as an emerging bioseparation technique and characterized with respect to its biochemical and thermal properties. These studies showed that this enzyme holds a great potential to be a good candidate for various industrial applications. To optimize fed-batch fermentation conditions, response surface methodology (RSM) was performed using face-centered central composite design. As a result, maximum PG activity (20.61 U/ml) and maximum biomass (34.23 g/l) were obtained at high maltrin (150 g/l) and high CSL (10 g/l) concentrations when the repeated feeding was done at 48th and 72nd hours. Maximum PMG activity (16.76 U/ml) was also achieved at higher maltrin and higher CSL concentrations at a feeding time of 72nd hours. Fed-batch fermentation has been successfully used to increase PG (33.74%) and PMG (23.96%) activities from Aspergillus sojae. Finally, agar diffusion method was adapted as a rapid method for the selection of high pectinase producer in the strain improvement study.