doktorska disertacija
Žiga Pandur (Author), David Stopar (Mentor), Matevž Dular (Co-mentor)

Abstract

Razpoložljivost neoporečne pitne vode postaja vse večja skrb v globaliziranem svetu. Kavitacija, kot nova obetajoča alternativna metoda pri procesu čiščenja vod, je pojav parnih mehurčkov v tekočinah ob hitrem lokalnem padcu tlaka, ki agresivno in hitro implodirajo, kar povzroča ekstremne fizikalno-kemijske razmere, ki imajo lahko uničujoč učinek na bakterije. Točen mehanizem inaktivacije bakterijskih celic s kavitacijo ni poznan. V doktorski disertaciji smo vpliv hidrodinamske in akustične kavitacije na lipidne vezikle, sferoplaste in bakterijske celice primerjali z vplivi fizikalno-kemijskih in mehanskih stresorjev. S selektivnim spreminjanjem izbranih komponent celične stene smo določili vpliv posameznih plasti na stabilnost celic pri kavitaciji in pokazali da je za stabilnost bakterij pri kavitaciji odločilen peptidoglikanski sloj. Za podrobnejše razumevanje interakcije med kavitacijskim mehurčkom in bakterijsko celico smo razvili novo metodo generiranja posameznega kavitacijskega mehurčka na mikrometrski časovni in prostorski skali, kar nam je omogočilo generiranje posameznega mikromehurčka v neposredni bližini bakterijske celice. Rezultati kažejo, da ima mikromehurček vpliv na bakterijske celice znotraj maksimalnega radija mikromehurčka. S pomočjo numeričnih analiz smo natančneje opisali razvoj kavitacijskega mehurčka in določili mejne sile, ki so potrebne za poškodovanje ali odtrganje celic iz površine. Rezultati te naloge prispevajo k bistveno bolj podrobnemu razumevanju kavitacije na nivoju posameznega mehurčka in njegovemu vplivu na bakterije, kar bo omogočalo nadaljnji razvoj metod kavitacije za namene čiščenja vode.

Keywords

kavitacija;kavitacijski mehurčki;bakterijska celična stena;liposomi;sferoplasti;mikroorganizmi;Escherichia coli;mehanizem inaktivacije;čiščenje voda;

Data

Language: Slovenian
Year of publishing:
Typology: 2.08 - Doctoral Dissertation
Organization: UL BF - Biotechnical Faculty
Publisher: [Ž. Pandur]
UDC: 532.528:579.2:577.352
COBISS: 134466051 Link will open in a new window
Views: 25
Downloads: 10
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Other data

Secondary language: English
Secondary title: Mechanism of action of the cavitation bubbles on bacterial cell
Secondary abstract: Due to escalating pollution, the world's clean water supplies are becoming seriously endangered. One of the novel promising methods in water cleaning is cavitation, where a sudden decrease in pressure triggers the formation of vapor and gas bubbles in a liquid medium. Fast and aggressive bubble implosions cause extreme physical-chemical conditions which inactivate bacteria and other contaminants. Despite an extensive research of cavitation, the exact mode of action on bacteria is not known. In doctoral dissertation we compare the effect of hydrodynamic and acoustic cavitation on lipid vesicles, spheroplasts and bacterial cells to the effect of various physio-chemical and mechanical stressors. Further, we evaluate the contribution of the individual cell wall layers on the resistance to cavitation. We show that peptidoglycan layer has the most important effect on cavitation resistance. For fundamental understanding of cavitation, we downscaled the cavitation phenomena to a single micrometer sized cavitation bubble and individual bacterial cell by developing a new method that delivers nanoscale spatial and temporal energy quantum to mechanically remove and destroy individual bacterial cells. The cavitation microbubble had an effect on bacterial cell when it was in proximity of the bubble. Numerical simulations enabled calculation of microbubble evolution and mechanical loads on bacterial cells and allow estimation of threshold values for wall shear stress and hydrodynamic force required for bacterial detachment and destruction. The new results will enable progress and development of cavitation technology towards more efficient and chemical free processes of water treatment.
Secondary keywords: cavitation;cavitation bubbles;bacterial cell wall;liposomes;spheroplasts;microrganisms;Escherichia coli;inactivation mechanism;water treatment;
Type (COBISS): Doctoral dissertation
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak.
Pages: 1 spletni vir (1 datoteka PDF (XI, 137 f., [75] f. pril.)
ID: 17448005