Master Degree / Yüksek Lisans Tezleri

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

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Subject: search.filters.subject.Biofilms

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Now showing 1 - 4 of 4
  • Master Thesis
    Investigation of the antimicrobial activities of polyphenols on biofilm-forming bacteria and characterization of polyphenol loaded-bone cements
    (01. Izmir Institute of Technology, 2024) Dağ, Hatice Damla; Dönmez, Ferda Soyer
    Bakteriler hızla antibiyotik direnci geliştirdiğinden, patojen bakterilerin neden olduğu enfeksiyonların önlenmesi veya tedavi edilmesi giderek zorlaşmaktadır. Periprostetik eklem enfeksiyonlarının tedavisinde antibiyotik yüklü kemik çimentolarının kullanılması enfeksiyon oranını azaltsa da, antimikrobiyal maddelerin yavaş salınımı antibiyotik direncini tetikleyebilmektedir. Bu nedenle bitkilerin sekonder metabolitleri olan polifenoller antimikrobiyal etkileri nedeniyle popülerlik kazanmıştır. Bu çalışmanın amacı iki farklı sınıf polifenolün (bir fenolik asit olan 3-HPAA ve bir flavonoid olan apigenin) biyofilm oluşturan patojen bakteriler üzerindeki antimikrobiyal etkilerini araştırmak ve 3-HPAA, apigenin, gentamisin, ve bunların kombinasyonları yüklü kemik çimentosu örneklerinin antimikrobiyal, sitotoksik ve mekanik dayanım özelliklerini incelemektir. Bu çalışma ile 3-HPAA'nın antibiyofilm özellikleri, 3-HPAA'ya karşı bakteriyel direnç gelişimi ve 3-HPAA veya apigenin yüklü kemik çimentosu örneklerinin karakterizasyonu ilk kez incelenmiştir. Bu amaçla 3-HPAA'nın antimikrobiyal ve antibiyofilm etkileri ve ardından 3-HPAA'ya karşı bakteriyel direnç gelişimi araştırılmıştır. Sonuç olarak 3-HPAA'nın MRSA ve P. aeruginosa üzerinde antimikrobiyal etki gösterdiği ve bu bakterilerin gentamisine direnç geliştirip 3-HPAA'ya direnç geliştirmediği belirlenmiştir. Ek olarak, gentamisin yüklü kemik çimentosu örneklerine 3-HPAA ve apigenin eklenmesinin antimikrobiyal etkileri altı farklı patojenik bakteri üzerinde farklılık göstermiş ve insan hücre hatları üzerinde herhangi bir sitotoksisite gözlemlenmemiştir. Son olarak 3-HPAA yüklü kemik çimentosu örnekleri, boş ya da gentamisin yüklü kemik çimentosu örneklerine kıyasla daha elastik ve dayanıklı gözlemlenmiştir.
  • Master Thesis
    Environmental Factors Influencing Bacterial Biofilm Formation and Inactivation
    (Izmir Institute of Technology, 2020) Üreğen, Mert; Baysal, Ayşe Handan; Özçivici, Engin
    Objective of this study was to evaluate effect of UV-C radiation (0, 1.16 and 3.21 kJ/cm2), pomegranate (Punica granatum) seed essential oil (PGEO) and lemon (Citrus lemonum) plant essential oil (CLEO) on decontamination of Candida albicans, Listeria monocytogenes, Staphylococcus aureus and Esherichia coli O157:H7 biofilms formed at +4°C and 20°C on polystyrene, stainless steel and glass surfaces. After 16, 32 and 64 sec UV-C treatment 0.24 log CFU/cm2, 1.61 log CFU/cm2, 1.59 log CFU/cm2 reductions were achieved in the numbers of C. albicans biofilms formed at 20°C on polystyrene. In the numbers of S. aureus biofilms formed at 20°C on polystyrene 0.99 log CFU/cm2, 1.9 log CFU/cm2, 3.91 log CFU/cm2 reductions were obtained after 16, 32 and 64 sec UV-C treatments, respectively. In general C. albicans biofilm formed at 20°C on stainless steel was found as the most UV-C resistant biofilm. CLEO inhibited the growth of C. albicans, L. monocytogenes and S. aureus at MIC values of 186 µg/ml, 103.5 µg/ml and 103.5 µg/ml, respectively. The results of the study showed that UV-C radiation and CLEO can be used as an anti-biofilm agent to control or to prevent biofilm formation of foodborne bacterial pathogens. It was suggested that UV-C radiation and CLEO treatments have potential as a biofilm control interventions for the food industry.
  • Master Thesis
    Physical and Antimicrobial Properties of Biofilms Containing Natural Antimicrobial Agents
    (Izmir Institute of Technology, 2008) Türe, Hasan; Özen, Fatma Banu
    The goal of this study is to evaluate physical and antimicrobial properties of biopolymers prepared from gluten (WG) and methyl cellulose (MC) with incorporation of activated lactoferrin (ALF), rosemary extract (RE) and natamycin (NA). The effectiveness of agents and antimicrobial films were investigated by agar disc diffusion method. Mechanical and water vapor permeability (WVP) of antimicrobial films were also examined. Film structure was investigated by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). Application of films was studied on Kashar cheese inoculated with target molds during 30 days storage at 10oC.ALF and RE did not show inhibitory activity against tested microorganisms.Minimum inhibitory concentration (MIC) of NA was found 750 ppm against Aspergillus niger and Penicillium roquefortii. Both films containing NA showed antifungal activity concentrations at and above 2 and 1 mg NA/10 g film solution (fs) against A. niger and P. roquefortii, respectively. RE in combination with NA reduced MIC of NA against A. niger to 1.5 mg NA/10g fs in both films. FTIR spectroscopy did not indicate any interaction between NA and both films. SEM observations showed that NA crystallizes at high concentrations in biopolymers. There was no significant change in WVP of films containing NA. Incorporation of NA to WG film did not cause major changes in its mechanical properties. Reduction in tensile strength of MC films was observed at high NA concentration. Application studies demonstrated the efficacy of WG and MC films including NA against A. niger and P.roquefortii inoculated on Kashar cheese.
  • Master Thesis
    Molecular Characterization of Biofilm Properties of Listeria Monocytogenes in the Presence of O-Coumaric Acid and 4-Hydroxybenzoic Acid
    (Izmir Institute of Technology, 2013) Ekin, Umut; Soyer Dönmez, Ferda
    Biofilms in medical and food industries are difficult to deal with. The formation of biofilms on every type of surfaces, ability to withstand in biofilm structures against thousand folds of lethal antibiotic doses and reasoning for different kinds of chronic diseases prove dangerousness of biofilms. Food borne pathogens that survive in biofilms can contaminate foods and feeding tubes which results food poisonings, outbreaks and infections. Listeria monocytogenes EGDe is one of the dangerous food borne pathogens with ability to form biofilms and cause listeriosis among elderly people, immunocompromised patients or pregnant women, which results lethal consequences. In this study, 4-hydroxybenzoic acid and o-coumaric acid that have potential antimicrobial and antibiofilm effect on Listeria monocytogenes EGDe were examined. Furthermore, protein profiles were investigated in the presence of phenolic acids. The antimicrobial assays of selected phenolic acids revealed the MICs against Listeria monocytogenes EGDe which are 18 mM for 4-hydroxybenzoic acid and 10 mM for ocoumaric acid. In the presence of MICs, while o-coumaric acid reduced initial attachment at 58%, 4-hydroxybenzoic acid reduced 48%. 4-hydroxybenzoic acid and ocoumaric acid also showed inhibitory effects on preformed biofilms as 34% and 56% respectively. The inhibitory effects of selected phenolic acids were ensured by visualization with SEM and Flourescence Microscopy. Afterwards, Listeria monocytogenes EGDe was treated with MIC of phenolic acids for total protein isolation. Isolated proteins were subjected to in-gel digestion and analysed in nanoLC-ESIMS/ MS system to interpret the mode of actions of antimicrobial and antibiofilming properties