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Vpliv faze rasti bakterijske kulture na pritrjevanje ter vpliv laminarnega toka tekočine na odstranjevanje pritrjenih bakterij : magistrsko delo
ID Robnik, Monika (Author), ID Bohinc, Klemen (Mentor) More about this mentor... This link opens in a new window, ID Fink, Rok (Co-mentor), ID Stopar, David (Co-mentor)

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MD5: 4CBDF24D5AE1623A5ED24F56E5B602D5
PID: 20.500.12556/rul/e4e0be3e-da68-46e3-aa2b-c468273eadb7

Abstract
Uvod: Vpliv biofilmov na biosfero zasledimo povsod. Prva faza v razvoju biofilma je adhezija bakterijskih celic. Nanjo vplivajo lastnosti površine, lastnosti bakterijske kulture ter medij, kateremu sta slednji izpostavljeni. Lastnosti bakterijske kulture so med drugim hidrofobnost, površinski naboj ter fiziološka faza rasti. Pritrjene bakterije lahko s površine odstranimo tudi s spreminjanjem jakosti strižnih sil, s hidrodinamskimi pogoji. Predhodne študije potrjujejo vpliv odstranjevanja bakterij s površin s spreminjanjem strižnih sil. Namen raziskave je ugotoviti optimalno fazo rasti bakterijske kulture, v kateri je pritrjevanje bakterije Bacillus subtilis najučinkovitejše, ter ali je te bakterije mogoče odstraniti s pomočjo laminarnega toka tekočine. Metode dela: V prvem delu raziskave smo ugotavljali količino bakterijskih celic na oksidirani bakreni površini v mirujočih pogojih. V drugem delu pa smo ugotavljali vpliv strižnih sil na odcepitev bakterijskega seva. Poskuse smo izvajali s pomočjo pretočne komore, ki ustvarja laminarni tok tekočine. Bakterijske celice smo opazovali s pomočjo fluorescenčne mikroskopije. Naredili smo tudi rastno krivuljo. Rezultati: Fiziološka faza rasti bakterijske kulture statistično značilno vpliva na pritrjevanje bakterije, saj smo ugotovili, da se največ bakterij Bacillus subtilis pritrdi v stacionarni fiziološki fazi rasti. Ugotovili smo tudi, da obstaja statistično značilna razlika med izpostavljanjem mirujoči tekočini ter laminarnem toku tekočine. Razprava in sklep: Z našimi rezultati nismo potrdili hipoteze, da je pritrjevanje Bacillus subtilis največje v eksponentni fazi rasti, saj smo ugotovili, da se najintenzivneje pritrjuje v stacionarni fazi. Na podlagi ugotovite lahko potrdimo drugo hipotezo, saj je laminarni tok odstranil večino pritrjenih celic, prav tako je bila razlika ocenjenega števila bakterij na površini v mirujoči tekočini in v maksimalnem laminarnem toku statistično značilna.

Language:Slovenian
Keywords:Bacillus subtilis, pritrditev, odstranitev, strižne sile, hidrodinamski pogoji, baker
Work type:Master's thesis/paper
Organization:ZF - Faculty of Health Sciences
Year:2017
PID:20.500.12556/RUL-98439 This link opens in a new window
COBISS.SI-ID:5364075 This link opens in a new window
Publication date in RUL:30.11.2017
Views:2246
Downloads:1046
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Secondary language

Language:English
Title:Impact of growth phase of the bacterial culture on bacterial adhesion and influence of laminar flow on bacterial detachment : master's degree thesis
Abstract:
Introduction: The impact of biofilms could be seen everywhere. Adhesion is the first phase of the development of biofilm. The properties of the surface, bacteria and medium (to whom they are exposed) affect the adhesion. The properties of the bacteria are: hydrophobicity, surface charge and physiological state of growth. The attached bacteria could be removed from surface also by changing the shear stress – hydrodynamic conditions. Purpose: The purpose of this study was to determine the optimal growth phase of the bacteria in which the adhesion of Bacillus subtilis is most effective. The aim was also to find out if the attached bacteria could be removed with the help of laminar flow regime. Methods: First we determined the quantity of the bacteria cells that were attached to copper coins in static conditions. After that we determined the impact of the shear stress on the adhered bacteria. The experiments were carried out using a flow chamber which created a laminar flow regime. The bacterial cells were observed by fluorescence microscopy. We also made a growth curve. Results: The adhesion of Bacillus subtilis was highest in the stationary physiological growth phase. Statistically, the physiological phase of the growth of bacterial culture significantly affects the attachment of the bacteria. We also found that there was a statistically significant difference between exposure to static conditions and the laminar flow regime. Discussion and conclusion: With our results, we did not confirm the hypothesis that the attachment of Bacillus subtilis is greatest in the exponential growth phase, as we have found that the most intense adhesion is in the stationary phase. On the basis of our findings, we can confirm the second hypothesis, because the laminar flow did remove the majority of the fixed cells. The difference between the static conditions and the maximum laminar flow regime was statistically significant.

Keywords:Bacillus subtilis, adhesion, detachment, shear stress, hydrodynamics conditions, copper

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