Keman, Deniz
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01. Izmir Institute of Technology
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Former Staff
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Sustainable Development Goals
1NO POVERTY
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2ZERO HUNGER
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3GOOD HEALTH AND WELL-BEING
2
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4QUALITY EDUCATION
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5GENDER EQUALITY
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6CLEAN WATER AND SANITATION
2
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7AFFORDABLE AND CLEAN ENERGY
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8DECENT WORK AND ECONOMIC GROWTH
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
2
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10REDUCED INEQUALITIES
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11SUSTAINABLE CITIES AND COMMUNITIES
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12RESPONSIBLE CONSUMPTION AND PRODUCTION
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13CLIMATE ACTION
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14LIFE BELOW WATER
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15LIFE ON LAND
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16PEACE, JUSTICE AND STRONG INSTITUTIONS
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17PARTNERSHIPS FOR THE GOALS
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Scholarly Output
5
Articles
3
Views / Downloads
26953/1152
Supervised MSc Theses
1
Supervised PhD Theses
1
WoS Citation Count
39
Scopus Citation Count
48
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0
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0
WoS Citations per Publication
7.80
Scopus Citations per Publication
9.60
Open Access Source
3
Supervised Theses
2
| Journal | Count |
|---|---|
| ACS Omega | 1 |
| Current Proteomics | 1 |
| Journal of Food Science and Technology | 1 |
Current Page: 1 / 1
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5 results
Scholarly Output Search Results
Now showing 1 - 5 of 5
Master Thesis Outer Membrane Protein Profiling of Escherichia Coli O157:h7 in Response To Phenolic Acid Stress(Izmir Institute of Technology, 2012) Keman, Deniz; Soyer Dönmez, FerdaEscherichia 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.Article Comparative Proteome Profiles of Methicillin-Resistant Staphylococcus Aureus in Response To Vanillic Acid and 2-Hydroxycinnamic Acid(Bentham Science Publishers, 2021) Keman, Deniz; Soyer, FerdaBackground: The ability of Staphylococcus aureus to cause severe infections and the difficulty of the treatments due to the multiple antibiotic resistance make this bacterium a lifethreatening human pathogen. This situation necessitates the exploration of novel antimicrobial compounds with known targets on bacteria. Phenolic acids naturally produced in plants as secondary metabolites are good candidates for being alternative antimicrobials for antibiotic-resistant bacteria. Objective: Investigation of protein profile of Methicillin-Resistant S. Aureus (MRSA) in the presence of subinhibitory concentrations of phenolic acids. Methods: MRSA was subjected to subinhibitory concentrations of Vanillic Acid (VA) and 2-Hydroxycinnamic Acid (2-HCA), separately, and the proteomic analyses were carried out by using liquid chromatography coupled to mass spectrometry. Results: Both phenolic acids elicited identification of differently expressed proteins that have roles in DNA replication, repair, RNA processing and transcription, protein synthesis, maintenance of cell homeostasis, several metabolic reactions in energy, carbohydrate and lipid metabolisms and also proteins related with the virulence and the pathogenicity of MRSA when compared with the control group. The numbers of the proteins identified were 444, 375, and 426 for control, VA-treated MRSA, and 2-HCA-treated MRSA, respectively, from which 256 were shared. While VA treatment resulted in 149 unidentified MRSA proteins produced in control, 2-HCA treatment resulted in 126 unidentified proteins. Data are available via ProteomeXchange with identifier PXD016922. Conclusion: The results obtained from this study might indicate the potential targets on bacteria and the effective use of phenolic acids in the battle with antibiotic-resistant pathogens.Article Citation - WoS: 27Citation - Scopus: 30Antibiotic-Resistant Staphylococcus Aureus Does Not Develop Resistance To Vanillic Acid and 2-Hydroxycinnamic Acid After Continuous Exposure in Vitro(American Chemical Society, 2019) Keman, Deniz; Soyer, FerdaDevelopment of resistance to antibiotics is one of the major reasons of difficulties in treatments of diseases caused by antibiotic-resistant bacteria, and this resistance makes the investigation of alternative antimicrobials a key priority. Phenolic acids are plant- and fungi-originating natural antimicrobial products, and there is no known bacterial resistance after exposure to them. The purpose of this study was to investigate the resistance ability of bacteria against phenolic acids. Therefore, the ability of methicillin-resistant Staphylococcus aureus and methicillin-susceptible S. aureus to gain resistance against two phenolic acids and an antibiotic upon exposure to subinhibitory concentrations was tested. Herein, we evaluated the minimum inhibitory concentrations (MICs) of vanillic acid (VA), 2-hydroxycinnamic acid (2-HCA), and vancomycin in the beginning of the experiment and the MICs were found to be 2.5 mg/mL VA, 1.6 mg/mL 2-HCA, and 0.01 mg/mL vancomycin for both bacteria. Following continuous treatments with increasing subinhibitory concentrations, MICs were evaluated once more. Exposure to subinhibitory concentrations of vancomycin induced the development of resistance immediately; however, resistance to both phenolic acids could not be induced. These data indicated the potential of phenolic acids to be used as effective antimicrobials in the inhibition of antibiotic-resistant pathogenic bacteria.Doctoral Thesis Investigation of Molecular Effect of Phenolic Acids on Methicillin-Resistant and Methicillin-Susceptible Staphylococcus Aureus in Comparison To Their Phenolic Acid Resistant Mutants(Izmir Institute of Technology, 2018) Keman, Deniz; Soyer, FerdaStaphylococcus aureus is a Gram-positive bacterium whose acquisition through an open wound results in various infections. Methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) strains are responsible for diseases ranging from soft tissue infections to fatal pneumonia which cannot be treated due to multiple drug-resistances of these strains. This situation increases the importance of searching for alternative antimicrobials worldwide. Having all these in mind, the capacity of phenolic acids cannot be denied to be used against pathogenic bacteria. Phenolic acids produced as plant secondary metabolites show antibacterial effects besides many beneficial properties for human health. The aim of this study was to investigate the antibacterial action mechanisms of vanillic acid and 2-hydroxycinnamic acid on MRSA and MSSA. To achieve this, firstly the antibacterial effects of phenolic acids on both bacteria were investigated by determination of minimum inhibitory concentrations. Then, the resistance development ability of bacteria against phenolic acids was tested by continuous exposure to subinhibitory concentrations. Finally, the action mechanisms of phenolic acids on bacteria were elucidated using two different proteomic approaches. According to the results, bacteria were not able to develop resistance against phenolic acids. Proteomic studies displayed alterations in the protein profiles of phenolic acid treated bacteria and provided potential targets in the battle with pathogenic bacteria. By showing the inability of MRSA and MSSA to develop resistance to phenolic acids and the important proteomic alterations that are induced by phenolic acid treatment, this study highlights the significance of phenolic acids to be used against antibiotic-resistant bacteria.Article Citation - WoS: 12Citation - Scopus: 18Synergistic Antimicrobial Effects of Activated Lactoferrin and Rosemary Extract in Vitro and Potential Application in Meat Storage(Springer Verlag, 2020) Soyer, Ferda; Keman, Deniz; Eroğlu, Erdal; Türe, HasanThis study aimed to explore the antimicrobial effects of activated lactoferrin (ALF) and rosemary extract (RE) on Escherichia coli O157:H7, Salmonella Enteritidis and Listeria monocytogenes, and to investigate their application potential in the meat storage. Minimum inhibitory concentrations (MICs) of ALF, RE and ALF-RE combinations were determined via microtiter plate assay. MICs of ALF were 1% for E. coli O157:H7; 0.5% for S. Enteritidis and 0.1% for L. monocytogenes. While 15% RE inhibited L. monocytogenes; 30% RE partially inhibited E. coli O157:H7 and S. Enteritidis growth. Synergistic effect of ALF and RE on the inhibition of E. coli O157:H7 increased the activity of ALF two to three folds. Food application of antimicrobials was performed by dipping of meat samples. Both ALF and RE were found effective in the prevention of L. monocytogenes growth about two logs. According to the data, choice of natural antimicrobials may be promising in food preservation.