Master Degree / Yüksek Lisans Tezleri

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

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Language: search.filters.language.enSubject: search.filters.subject.Phenolic acids

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Now showing 1 - 5 of 5
  • Master Thesis
    Investigation of Antimicrobial Properties of 4-Hydroxybenzoic Acid and Its Application in Bone Cement
    (01. Izmir Institute of Technology, 2022) Soyer, Ferda; Dokumacı, Ecem; Soyer Dönmez, Ferda; 01. Izmir Institute of Technology; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science
    The bone cement is composed of polymethylmethacrylate powder and liquid methylmethacrylate which is commonly used in clinical applications. Nosocomial pathogens utilize the bone cement surface to induce infections, so that bone cements are loaded with various antibiotics to inhibit the infection. Nevertheless, the bacteria gain resistance against antibiotics since the antibiotics are released at slow rates. Phenolic acids are secondary metabolites of plants to prevent infections; thus, are promising antimicrobial chemicals against pathogens. The main aim of this study is the investigation of the antimicrobial effect of liquid and powder 4-hydroxybenzoic acid-loaded bone cement on Escherichia coli, methicillin-resistant and susceptible Staphylococcus aureus. Previously, liquid and powder vancomycin-loaded bone cement had been studied against MRSA and Candida albicans, caffeic acid-loaded bone cement is also investigated on the S. aureus. This study will be the first investigation that the antimicrobial effect of liquid and powder phenolic acid-loaded bone cement against pathogens. 4-HBA was added directly into polymethylmethacrylate powder and mixed with liquid methylmethacrylate. Cement discs were prepared by metal mold and the antimicrobial assay was carried out to determine the bacterial growth inhibition. The structural features of bone cements such as pores and surface were characterized SEM. The antimicrobial agent release of bone cement was also examined by spectrophotometer and HPLC was used for confirmation. Resistance development against 4-HBA was tested on MRSA and Acinetobacter haemolyticus by exposing them to the sub-inhibitory concentrations. The possible genes for the resistance were checked by ddPCR. The significant inhibition of bacterial growth by 4-HBA-loaded bone cement is expected and liquid 4-HBA is expected to be released at a higher rate. Therefore, the phenolic acids may be used as antimicrobial agents in bone cement to inhibit pathogenic bacterial growth.
  • Master Thesis
    Investigation of Protein Profiles of Listeria Monocytogenes in the Existence of Phenolic Acids Using Mass Spectrometry
    (Izmir Institute of Technology, 2020) Soyer, Ferda; Yalçın, Talat; Yalçın, Talat; Soyer Dönmez, Ferda; 04.03. Department of Molecular Biology and Genetics; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Listeria monocytogenes is one of the foodborne pathogens (FBP), which are a threat to the consumers' health, able to cause listeriosis. L. monoytgenes cells, which can easily adapt and survive stresses, can develop resistance to antibiotics used in standard therapy. Phenolic acids that are a natural defense mechanism against stress conditions in plants, might be used as an antibacterial-candidate in foodborne diseases, so there is a need for a better understanding of the stress-induced responses and mechanisms of bacteria against these substances. Proteomic approaches are an invaluable method for identifying the stress response in pathogenic bacteria. For this purpose, in this study firstly, the antibacterial effects of two phenolic acids (3-HPAA and 4-HBA) on bacteria were investigated by determining the minimum inhibitory concentrations (MIC). Subsequently, target changes in the protein profile due to antimicrobial effects of phenolic acids were evaluated using a soft ionization technology and mass spectrometry-based comparative gel-free proteomic approach (Shotgun proteomics). According to the results, Listeria monocytogenes could not develop resistance to both phenolic acids. This study emphasizes the importance of using of phenolic acids as a novel and natural therapy methods to overcome antibiotic-resistant pathogenic bacteria.
  • Master Thesis
    A Proteomic Analysis of the Response of Listeria Monocytogenes To the Stress Induced by O-Coumaric Acid and Ferulic Acid
    (Izmir Institute of Technology, 2013) Cerit, Ender Efe; Soyer, Ferda; Soyer Dönmez, Ferda; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Phenolic acids are known for their potential antimicrobial action, however their mechanisms of action are still unraveled. In this study, effect of phenolic acid stress on Listeria monocytogenes, a dangerous foodborne pathogen, was studied with a proteomic approach. Two phenolic acids found in olive oil, namely o-coumaric acid and ferulic acid, were applied on this bacterium via microtiter plate assay. The concentrations of these phenolic acids that inhibit the bacterial growth by 50% were determined as 7.5 mM for o-coumaric acid, and 8 mM for ferulic acid. Besides, minimum bactericidal concentration of o-coumaric acid was also found as 12 mM. Cellular proteomes of phenolic acid-treated and untreated bacteria were analysed with nanoLC-ESI-MS/MS system, and identified with MaxQuant/Andromeda bioinformatic toolbox. According to the results, both phenolic acids induced oxidative stress in L. monocytogenes cells. In addition to this, DNA replication and repair enzymes, nutrient uptake proteins and several proteins directly related with the virulence of L. monocytogenes were among the targets of phenolic acid stress. Last but not least, proteins associated with biosynthetic pathways were found to be predominantly downregulated. Moreover, the morphology of phenolic acid-treated and untreated cells was visualized with scanning electron microscope to support these findings. The images showed that lengths of treated cells were either abnormally elongated or shortened when compared to untreated cells. A possible reason for these abnormalities is the unequal fission promoted by two factors; excessive production of cell envelope biosynthesis and fission regulatory proteins, and repression of aforementioned DNA replication and repair enzymes.
  • Master Thesis
    Characterization of Outer Membrane Proteins of Salmonella Enteritidis in Response To Phenolic Acids Stress
    (Izmir Institute of Technology, 2012) Özdemir, Özgün Öykü; Soyer, Ferda; Soyer Dönmez, Ferda; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) is one of the most reported foodborne pathogen bacterium throughout the world that causes large outbreaks and may result in deaths. Phenolic acids, synthesized in almost all plants, are important for plant metabolism and protection of plants. They can be thought as promising antimicrobial agents against Salmonella Enteritidis. Outer membrane proteins are unique structures to Gram-negative bacteria including Salmonella genus and they are the first targets to environmental changes. This study showed the antimicrobial effect of 3-HPAA, cinnamic acid and o-coumaric acid on Salmonella Enteritidis in vitro. Scanning electron microscopy was used for showing the changes in bacterial shapes. Their effects on the outer membrane protein profile were investigated via proteomic approach. According to results of 96-well microtiter plate assay used for antimicrobial effect determination, among these phenolic acids, 3-HPAA showed 100% growth inhibition and other phenolics retarded the bacterial growth. 30 mM was found as minimum inhibitory concentration (MIC) of 3-HPAA at 24th hour of the experiment. SEM results demonstrated that 3-HPAA causes bacteria to have collapses on cell surface while cinnamic acid and o-coumaric acid cause cells to elongate abnormally. SDS PAGE of the OMPs of bacteria who were exposed to phenolic acids showed changes in amounts of proteins in some protein bands compared to control OMPs. 2-D PAGE results of OMPs of control bacteria via OMPs of 3-HPAA, cinnamic acid and o-coumaric acid treated bacteria, changes in sizes of spots were observed.
  • Master Thesis
    Outer Membrane Protein Profiling of Escherichia Coli O157:h7 in Response To Phenolic Acid Stress
    (Izmir Institute of Technology, 2012) Keman, Deniz; Keman, Deniz; Soyer, Ferda; Soyer Dönmez, Ferda; 01. Izmir Institute of Technology; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science
    Escherichia coli O157:H7 is a Gram-negative foodborne and waterborne pathogenic bacterium. Low doses of E. coli O157:H7 are adequate for infection that results in clinical cases, namely hemorrhagic colitis, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome. These diseases can be lethal for children, elderly and immunocompromised people. Phenolic acids are herbal secondary metabolites. They are important for the response to environmental stresses. They are significant for human diet due to their health beneficial properties. The objective of this study was the elucidate the antimicrobial mode of action of selected phenolic acids against E. coli O157:H7. The antimicrobial activities of caffeic, rosmarinic, and vanillic acids on E. coli O157:H7 were investigated via microtiter plate assay. Minimum inhibitory concentrations were found as 6.5 mM for caffeic acid, 15 mM for rosmarinic acid and 8 mM for vanillic acid by applying a range of concentrations for each phenolic acid against the bacteria. Effect of each phenolic acid on the cell surface of E. coli O157:H7 was visualized by scanning electron microscopy. Microscopic examination demonstrated that while the surfaces of control group E. coli O157:H7 remained intact, cells treated with phenolic acids displayed disrupted cell surfaces. The bacteria were treated with each phenolic acid at a concentration which resulted in 30-50% inhibition for evaluation of outer membrane protein (OMP) profiles in response to phenolic acids stress. Following OMP isolation, SDS-PAGE and 2D-PAGE analyses were performed. By examining the OMP profiles of phenolic acid treated-bacteria, differences in expression of some proteins were observed.