Master Degree / Yüksek Lisans Tezleri

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Author: search.filters.author.Büyükkileci, Ali OğuzPublisher: search.filters.publisher.Izmir Institute of Technology

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Now showing 1 - 9 of 9
  • Master Thesis
    Effects of Centella Asiatica Saponins on Telomerase Activation and Wound Healing
    (Izmir Institute of Technology, 2021) Demirbaş, Devran; Büyükkileci, Ali Oğuz; Bedir, Erdal; Bedir, Erdal; Büyükkileci, Ali Oğuz; 03.01. Department of Bioengineering; 01. Izmir Institute of Technology; 03.08. Department of Food Engineering; 03. Faculty of Engineering
    Centella asiatica L. is a well-known plant species endemic to Southeast Asia that has noteworthy biological effects. Triterpenoid saponins, comprising more than 80% of the content, are suggested to be the chief compounds responsible for the biological effects. A recent study has described that the extract of Centella asiatica exhibits telomerase activation. In line with these developments, as part of our studies on natural products demonstrating anti-aging properties, we decided to engage Centella asiatica and its components. Within the scope of this thesis, four major compounds, viz. madecassoside, asiaticoside, madecassic acid, and asiatic acid were isolated from the standardized extract of Centella asiatica, and their structures were elucidated by spectroscopic methods. Using in vitro methods, the effects of the extract and purified compounds on cell proliferation under standard culture and oxidative stress (H2O2) conditions, wound healing, and human Telomerase Reverse Transcriptase (hTERT) protein level were investigated. Our experiments were conducted on MRC-5 and HEKn cell lines. It was observed that the standardized extract of Centella asiatica increased the proliferation of the MRC-5 cells meaningfully between 5 to 100 µg/ml. Moreover, the extract showed protective effects on MRC-5 cells at 500 and 1000 ng/ml under oxidative stress conditions. Madecassoside, madecassic acid, asiaticoside, and asiatic acid exhibited the highest proliferative effects on MRC-5 cells at concentrations of 1000 nM (28%), 2 nM (66%), 300 nM (61%), and 300 nM (56%), respectively. Asiatic acid and the extract accelerated cell migration in wound areas that were made on MRC-5 cells up to 32% and 36% in the range of 10 to 300 nM or ng/ml, respectively. The immunoblotting assay studies showed that madecassoside and asiaticoside were increased the expression of hTERT protein level on HEKn cell line by 3.16-fold and 5.62-fold, respectively, at 30 nM concentration. Furthermore, the extract was observed to increase the protein level by 2.62-fold at 300 ng/ml.
  • Master Thesis
    Induction of Secondary Metabolism of Some Marine Derived Streptomyces Species, and Isolation and Identification of Their Bioactive Secondary Metabolites
    (Izmir Institute of Technology, 2020) Gezer, Emre; Büyükkileci, Ali Oğuz; Bedir, Erdal; Gezer, Emre; Bedir, Erdal; Büyükkileci, Ali Oğuz; 03.01. Department of Bioengineering; 01. Izmir Institute of Technology; 03.08. Department of Food Engineering; 03. Faculty of Engineering
    Secondary metabolites are natural products with low molecular weight produced by different organisms. These metabolites have a wide variety of bioactivities because of their adaptive roles in the nature. These properties make secondary metabolites important source in drug discovery studies. Streptomyces genus, on the other hand, attracts attention due to their ability to produce many secondary metabolites for the treatment of various diseases, especially infectious diseases and cancer. However, secondary metabolism is not fully expressed under standard laboratory conditions as in nature. This phenomenon limits the discovery of new/novel bioactive molecules from the microbial sources. In this study, a previously studied marine derived actinobacterium, namely Streptomyces cacaoi, was investigated further to discover new antimicrobial metabolites via medium and temperature optimization using Box Behnken design. As a result, GPM medium containing 2.25% glycerol, 1% peptone water, 0.2% CaCO3, 0.1% MgCl2 in distilled water was found to provide the highest chemical diversity with potent bioactivity at 30oC. In subsequent studies, inductive effects of some microorganisms and inorganic compounds on secondary metabolism were also determined. Using optimized conditions, a larger fermentation study was undertaken (25 L) followed by extraction and isolation procedures. Sixteen metabolites were purified by chromatographic methods, and structures of the isolates were elucidated by spectral methods. Thirteen compounds, five of which were new, were members of polyketide-type polyether antibiotics. The structures of other molecules were determined as cyclo(Thr-Trp), 6-hydroxy-6-methyloctanoic acid, and 5-hydroxy-1,6-diazacycloundec-5-en-2-one, and all were found to be new. In antimicrobial tests, most polyethers were found to be active against Gram-positive bacteria. In particular, two new polyethers SC-EG-05 and SC-EG-07 showed higher antimicrobial activity than widely used antibiotic vancomycin
  • Master Thesis
    Extraction of Phytochemicals From Scolymus Hispanicus and Determination of Potential Health Effects
    (Izmir Institute of Technology, 2017) Ahmad, Bilal; Büyükkileci, Ali Oğuz; Güleç, Şükrü; Büyükkileci, Ali Oğuz; Güleç, Şükrü; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Golden thistle (Scolymus hispanicus) is an edible medicinal plant growing in Turkey. It has been in use since decades for the treatment of various disorders by local folks. In the past the extracts from the root barks of S. hispanicus were in use in the form of a medicine for the removal of kidney stones. Its root barks are the only eaten part and the root internal and aerial parts are considered as residues. The effect of harvesting time and plant maturity on phytochemicals composition of this plant have not been studied before. Besides that, in previous studies only the edible part was analyzed for bioactive constituents and the residues (aerial parts and root internal parts) have not been analyzed before. In this study, various phytochemicals and total antioxidant activities in the ethanol extracts of aerial parts, root barks and root internal tissues of S. hispanicus harvested from November 2016 to July 2017 were measured. The dominant phytochemicals were different in the roots and the aerial parts, whereas phytochemicals were influenced differently by the harvesting time. Total phenol contents and total antioxidant activities were higher in the aerial parts than the root parts, while total triterpenoid contents were higher in root barks and root internal tissues. Thin Layer Chromatography (TLC) analysis showed that there were not any free triterpenoids in the extracts, however there were glycosides, which may have contained triterpenoids. The crude extracts of S. hispanicus showed cytotoxic effects on Caco-2 cells growth. The results suggested that these extracts might have potential preventative effects on colon cancer.
  • Master Thesis
    Xylan Degradation Mechanism of Human Intestinal Bacteria
    (Izmir Institute of Technology, 2017) Polat, Nüket; Güleç, Şükrü; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; Güleç, Şükrü; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Xylan is the second most abundant plant cell wall polysaccharide after cellulose. The xylan rich lignocellulosic material obtained from agriculture, forestry and industrial wastes provides cost effective raw materials. The degradation of xylan in the human body is an important process contributing to the continuation of the microbial communities living in the human colonic ecosystem. Due to its complex, long chain structure and the various chemical bonds it contains, xylan hydrolysis requires different enzymatic activities. Bacteria that live in the colon and are useful for human health, such as Bifidobacterium and Lactobacillus species can not perform xylan utilization. However, several types of xylan are utilized by the Bacteroides species, which have the second largest density in the colon. In this study, different Bifidabacterium and Bacteriodes species were investigated for their ability to degrade beechwood xylan and corncob xylan. Bifidabacterium and Bacteriodes were cultured together in tubes containing xylan as the sole carbon source. It was observed that; the B. animalis subsp. lactis, which does not have the ability to use the xylan, could grow when cultured on xylan-containing medium with Bacteroides species. These showed that, the xylan in the media was degraded into xylooligosaccharides by the Bacteroides species and the XOS formed was used as a carbon source by both species. The short chain fatty acid and lactic and succinic acid production profiles of co-cultures were different than the mono cultures, indicating a positive effect of co-culturing. This study showed that xylan is a potential prebiotic carbohydrate, which can selectively stimulate the growth of beneficial bacteria in the colon, as a result of possible cross feeding of different bacteria residing in the colon.
  • Master Thesis
    Pretreatment Methods for Valorization of Hazelnut Pruning Wastes
    (Izmir Institute of Technology, 2016) Doğru, Kevser; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Turkey is the world leader in hazelnut production and a large amount of residues is produced during its harvesting and processing. So far, the residues of hazelnut production had no economic value and usually burned in the fields. Obtaining valuable products such as ethanol from hazelnut pruning waste (HPW) can add value to those. Ethanol produced by microorganisms via fermentation is a promising alternative biofuel. Ethanol has been produced for a long time from sugary substances, while lignocellulosic biomasses (LCBs) are interesting alternative to fossil fuel based resources in order to have a sustainable production process. Liquid hot water (LHW) treatment is one of the pretreatment processes necessary to facilitate enzymatic hydrolysis of cellulose into glucose before ethanol fermentation. Organosolv is similar to LHW treatment except that ethanol-water mixture is generally used is the liquid part instead of only water. LHW could remove the hemicelluloses from the lignocellulosic matrix to some extent, while adding H2SO4 improved the hemicellulose removal. Organosolv was effective on removal of lignin as well as of hemicellulose. Acid catalysis improved the hemicellulose solubilization in organosolv, like in LHW treatment. After acid catalyzed organosolv, cellulose content of the HPW was increased to 67.91%. This sample was hydrolyzed with a conversion efficiency of 87.32%. Hydrolysate containing 60.63 g/L glucose was used as the medium for ethanol production using Saccharomyces cerevisiae. At an 83.49% theoretical yield, 22.2 g/L ethanol was obtained after 6 h. These results demonstrated that hazelnut pruning waste has potential to be used as a feedstock for ethanol production.
  • Master Thesis
    Investigations on the Effects of Carbon Sources and Ph on Exo-Polygalacturonase Productions by Aspergillus Sojae
    (Izmir Institute of Technology, 2013) Kuru, Gülten; Büyükkileci, Ali Oğuz; Kuru, Gülten; Büyükkileci, Ali Oğuz; 01. Izmir Institute of Technology; 03.08. Department of Food Engineering; 03. Faculty of Engineering
    Pectinases are a group of enzymes that are responsible for degredation of pectic substances. Pectinases are produced by many organisms including plants, bacteria and fungi. The aim of this study was to investigate the effect of different carbon sources and pH on pectinase production by a group of flamentous fungi. For this purpose, Aspergillus niger, Rhizopus oryzae ATCC 4858, Aspergillus sojae ATCC 2035 (A. sojae WT) and its mutant type Aspegillus sojae MT (A. sojae MT) grown in orange peel containing media were evaluated in terms of exo-polygalacturonase (exo-PG), pectin lyase (PL), pectin methyl esterase (PME), and also xylanase and cellulase activities. A. sojae WT and A. sojae MT were found to be as exo-PG producers. Maximum exo-PG activities were 47.84 U/ml and 108.02 U/ml, respectively. Exo-PG production by A. sojae WT and A. sojae MT was evaluated using the medium containing glucose, pectin, pectin/glucose, pectin/fructose and pectin/sucrose as substrate. Additional supply of glucose to the pectin media was found to be more effective than fructose or sucrose. The fermentations in which pH was not maintained, the use of glucose, pectin and pectin/glucose resulted in superior enzyme activities compared to ones obtained with other media compositions.
  • Master Thesis
    Utilization of Organce Peel Extract for Fungal Enzyme Production
    (Izmir Institute of Technology, 2013) Genç, Berna; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Pectinases are a group of hydrolytic enzymes that degrade pectic substances and produced by a variety of microorganisms including filamentous fungi. In previous studies orange peel especially in solid state fermentations was utilized as a source of additional sugars and nutrients. In this study, orange peel, an agro industrial residue was used for exo-polygalacturonase (exo-PG) production in submerged fermentation (SmF) by Aspergillus sojae which have been shown to be a potential exo-polygalacturonase producer. Solubilization of carbohydrates within orange peel was provided by water extraction and treatment with dilute phosphoric (at 0.4% acid concentration and 120 oC in 20 min.) and sulfuric (at 0.5% acid concentration and 116 oC in 13 min.) acid hydrolysis. Phosphoric acid hydrolysis was optimized selecting temperature (oC), time (min.) and acid concentration (v/v %) as variable factors, while reducing sugar concentration (gL-1) was the response factor. Two different dilute acid hydrolysis (at 0.4 % phosphoric acid concentration and 120 0C in 20 min and at 0.5 % sulfuric acid concentration and 116 0C in 13 min.) and water extraction were carried out to obtain media that were utilized for enzyme productions. A.sojae ATCC 20235 and mutant A.sojae strains were used to produce exo-PG in these hydrolysates and water extract of orange peel. To enhance exo-PG production, trace element solutions added as well as macro nutrients. Pellet size, number, density, pH and spore inoculation of fermentation were the other parameters that were controlled during fermentations. The highest exo-PG production was 18.4 UmL-1, which was obtained by mutant A.sojae in phosphoric acid hydrolysate but on the other hand mutant A.sojae produced 19.7 UmL-1 exo-PG activities in water extract of orange peel.
  • Master Thesis
    Utilization of Wine Waste for Fermentative Processes
    (Izmir Institute of Technology, 2013) Bayrak, Emrah; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Grape pomace is generally considered as most valuable waste of winemaking process. Two different grape types of Syrah (red) and Muscat (white) were collected in the middle of the harvest season after pressing steps of both red and white wine making process Carbohydrate content of grape pomace was hydrolysed by enzymatic and acid hydrolysis. After screening possible fermentable sugars of grape pomace lactic acid fermentation were performed from grape pomace suspension and liquid extract phase. Lactic acid fermentation by Lactobacillus casei showed that grape pomace can be used as a substrate for lactic acid production. Different solid loadings and yeast extract concentrations effect the lactic acid production yield from grape pomace. Enzymatic hydrolysis was performed to hydrolyse pectin, cellulose and hemicellulose of grape pomace. Commercial pectinase, cellulase and β-glucosidase were supplemented into grape pomace suspensions at different concentrations. Maximum hydrolysed glucose and xylose from extracted solid phase of grape pomace were calculated as 8.93 ± 0.21 and 4.52 ± 0.11 % of total solid. Furthermore, acid hydrolysis showed that two stages acid hydrolysis is more efficient in releasing glucose from extracted solid phase of grape pomace but dilute acid hydrolysis is also more efficiency on hydrolysis of xylose and arabinose. Exo-polygalacturonase production from grape pomace was conducted using different filamentus fungi, namely Aspergillus sojae, Rhizopus oryzae and Aspergillus niger but no significant enzyme activity was obtained. Maximum 84 % of fermentable sugar in dry grape pomace was converted to lactic acid by L. casei. Effect of yeast extract researches designated that commercial yeast (bakers’ yeast) can be used as nitrogen source instead of yeast extract and 10 g/l of yeast extract was the most suitable concentration for lactic acid production from grape pomace by L.casei. This study showed the potential of the grape pomace for fermentative processes.
  • Master Thesis
    L(+)lactic Acid Production From Whey by Lactobacillus Casei Nrrl B-441
    (Izmir Institute of Technology, 2000) Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Lactic acid, its derivatives and poly-lactic acid are widely used in the industry. Lactic acid has been produced chemically or by fermentation for many years. However, there is a need to develop low cost production and purification methods. The development and use of processes with high productivity and product yield from inexpensive carbohydrate sources can lead to a more feasible lactic acid production.The goal of this work was to find the most suitable values of some fermentation parameters for lactic acid production from whey by an L-lactic acid producing bacterium, Lactobacillus casei. Whey is the by-product of cheese production and it is inexpensive and year-round available.Fermentations were conducted in the fermenter and shake flasks to determine the optimum values for temperature and pH. The highest lactic acid productivity values were obtained at 37 a1C and pH 5.5. The productivity was 2.0 g r1 h-1 at 37 a1C in the shake flask. In the fermenter, a productivity of 4.6 g r1 h-1 was obtained at pH 5.5. The effect of yeast extract concentration was also examined. Although the productivity values were found to be slightly higher (approximately 1.8-2.0 g r1 h-1 with 0.75 and 1.0% (w/v), 0.5% (w/v) yeast extract concentration with a productivity figure of 1.75 g r1 h-1 was concluded to be the most feasible concentration, since yeast extract is an expensive material.1. casei was tested for its capability to utilize different substrates, particularly whey, synthetic lactose and synthetic glucose. Whey yielded a higher productivity value of 1.75 g r1 h-1 than the synthetic sugars.The effect of initial substrate concentration on lactic acid production was examined up to 10% (w/v) whey lactose. Lactose was utilized completely for every initial substrate concentration examined in this study. Product yields were between 0.89-0.94 g lactic acid (g lactose r1 The salt effect was examined by discarding one of the salts (K2HP04, KH2P04, MgS04 or MnS04"H20) from the medium at each run. The lactic acid production was poor in the absence of MnS04.Seed culture that had the same composition as the fermentation medium was used as the inoculum for the fermenter. With this seed culture greater productivity values were obtained than the shake flasks, which were inoculated with litmus milk culture. In the shake flasks the highest productivity was around 2.0 g r1 h-1, while in the fermenter a productivity value of 4.6 g r1 h-1 could be obtained with 12.5% inoculum at pH 5.5. Biomass growth was investigated in lactose synthetic medium. The lactic acid production was associated with the biomass growth up to a certain time, but then a non-growth associated lactic acid production was observed. Maximum specific growth rate was calculated as 0.32 h-1.