doktorska disertacija
Mojca Krajnc (Author), David Stopar (Mentor), Polonca Štefanič (Co-mentor)

Abstract

Bacillus subtilis je pogost modelni sistem za preučevanje nastanka biofilma. V študiji smo povezali razvoj plavajočega biofilma na interfazi voda-zrak s porazdelitvijo in sposobnostjo preživetja posameznih celic B. subtilis v vodnem stolpcu. Z uporabo IRS in CLSM metod smo korelirali morfološke spremembe z mehanskimi lastnostmi rastočega plavajočega biofilma. Identificiranih je bilo šest ključnih dogodkov, ki jih spremlja velika sprememba v morfološkem in viskoelastičnem obnašanju biofilmov. Rezultati kažejo, da je razvoj plavajočega biofilma večplasten odziv na spreminjajoče se okolje, ki ga omogoča rast bakterij, kar povzroči prerazporeditev populacije znotraj modelnega sistema, redukcijo ustreznega habitata na interfazo voda-zrak, razvoj celic in morfogenezo. Propad plavajočega biofilma, ko biofilm izgubi sposobnost prenašanja mehanskih obremenitev, korelira s procesom sproščanja endospor in vstopom sistema v stanje mirovanja. Z gojenjem genetsko heterogenih plavajočih biofilmov smo določili vpliv sorodnosti med sevi na nastanek in razvoj mešanega plavajočega biofilma. Pokazali smo, da v kombinacijah manj sorodnih sevov dominantni sev lahko popolnoma zavre rast in razvoj manj sorodnega seva. Z gojenjem manj sorodnih sevov v mikropretočni napravi smo na nivoju posameznih celic pokazali, da se najprej oblikujejo prostorsko razpršeni agregati sevov do zapolnitve prostora mikrokomore, nato dominantni sev postopno zmanjša gostoto celične populacije manj sorodnega seva in ga izloči. S spreminjanjem začetnega deleža sevov, ki so vključeni v interakcijo smo pokazali, da je izid interakcije med genetsko manj sorodnimi sevi bakterije B. subtilis odvisen od začetnega razmerja konkurenčnih sevov.

Keywords

B. subtilis;plavajoči biofilm;sorodstveno razlikovanje;CLSM;IRS;mikrofluidika;

Data

Language: Slovenian
Year of publishing:
Typology: 2.08 - Doctoral Dissertation
Organization: UL BF - Biotechnical Faculty
Publisher: [M. Krajnc]
UDC: 579.22/.26:579.852.11:532.12/.13
COBISS: 164247299 Link will open in a new window
Views: 23
Downloads: 15
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Other data

Secondary language: English
Secondary title: Biology and mechanics of Bacillus subtilis biofilm
Secondary abstract: Bacillus subtilis is a common model system for studying biofilm formation. In the study, we have linked the development of a floating biofilm at the water-air interface with the distribution and viability of individual B. subtilis cells in the water column. Using IRS and CLSM methods, we have correlated the morphological changes with the mechanical properties of the growing floating biofilm. Six key events in biofilm development accompanied by a large change in morphological and viscoelastic behaviour were identified. The results show that the development of the floating biofilm is a multifaceted response to the changing environment facilitated by bacterial growth, resulting in population redistribution within the model system, reduction of suitable habitat to the water-air interface, cell development, and morphogenesis. The collapse of the floating biofilm, when the biofilm loses its ability to bear mechanical loads, correlates with the process of endospore release and the system entry into a state of rest. By growing genetically heterogeneous floating biofilms, we have determined the influence of relatedness between strains on the formation and development of mixed floating biofilms. We have shown that in combinations of less related strains, the dominant bacterial strain can completely suppress the growth and development of the less related strain. By growing less related strains in a microfluidic device we have shown that spatially dispersed aggregates of different strains are formed until the microchamber is filled, then the dominant strain gradually reduces the density of the cell population of the less related strain and eliminates it. By changing the initial ratio, we have shown that the outcome of the interaction is strongly dependent on the initial ratio of competing strains.
Secondary keywords: B. subtilis;floating biofilm;kin discrimination;CLSM;IRS;microfluidics;
Type (COBISS): Doctoral dissertation
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak.
Pages: 1 spletni vir (1 datoteka PDF (XI, 70 f., [16] f. pril.)
ID: 19929389