magistrsko delo
Tea Skočič (Author), Sonja Smole Možina (Reviewer), Ines Mandić-Mulec (Mentor), Ines Mandić-Mulec (Thesis defence commission member), Tjaša Danevčič (Thesis defence commission member), Mojca Narat (Thesis defence commission member), Sonja Smole Možina (Thesis defence commission member), Tjaša Danevčič (Co-mentor)

Abstract

Po Gramu-pozitivne talne bakterije vrste Bacillus subtilis so zaradi izmeničnega izsuševanja in vlaženja tal pogosto izpostavljene spremembam v osmolarnosti, ki upočasnijo rast in sprožijo procese prilagajanja. Bakterija B. subtilis zaznava dinamiko rasti s sistemom za zaznavanje kvoruma ComQXPA, ki vpliva na razvoj biofilmov. Ni znano ali in kako ta sistem vpliva na razvoj biofilmov pri povišani slanosti. Cilj magistrske naloge je bil preveriti morfologijo, razrast in biomaso biofilma divjega tipa B. subtilis in signalnih mutant v gojišču MSgg z različno vsebnostjo NaCl (0, 2, 4, 6 % (w/V)). Uporabili smo nabor različnih signalnih mutant in mutant okvarjenih v odzivu na signal ComX: ΔcomQ, ΔcomP, ΔcomA, ΔsrfA in ΔcomQ ΔsrfA. Spremljali smo tudi viskoznost divjega tipa in mutant comQ, srfA in comQ srfA, ter pri divjem tipu in mutanti comQ tudi izražanje promotorja gena epsA. Ugotovili smo, da povišana slanost gojišča upočasni razvoj ter zniža biomaso, viskoznost in nagubanost biofilma divjega tipa. Signalni mutanti comQ in comP tvorita oba tipa biofilma (pelikel in kolonijo) hitreje kot divji tip pri vseh slanostih gojišča, medtem ko je razvoj biofilmov mutant srfA, comQ srfA in comA primerljiv oziroma hitrejši le pri povišani slanosti gojišča. Biofilm signalnih mutant je bolj viskozen kot biofilm divjega tipa, vendar dinamika izražanja promotorja gena epsA pri signalni mutanti ne razloži povišane viskoznosti. Na podlagi pridobljenih rezultatov sklepamo, da sistem za zaznavanje kvoruma ComQXPA bakterije B. subtilis zavira razvoj biofilma pri različnih slanostih gojišča.

Keywords

biotehnologija;Bacillus subtilis;zaznavanje kvoruma;osmotski stres;razvoj biofilma;morfologija biofilma;viskoznost biofilma;surfaktin;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [T. Skočič]
UDC: 602.3:579.852.11:579.23(043.2)
COBISS: 8897145 Link will open in a new window
Views: 1564
Downloads: 231
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Other data

Secondary language: English
Secondary title: Link between quorum sensing and response to high salinity in Bacillus subtilis
Secondary abstract: A Gram-positive soil bacterium Bacillus subtilis is often exposed to osmolarity changes due to alternate flooding and drying of soil. Osmotic stress may damage bacterial cells and slow their growth, but it also induces an adaptive response that helps bacteria survive osmolarity changes. B. subtilis monitors the population growth by the ComQXPA quorum sensing (QS) system that also affects biofilm development. However, it is not known whether and how this quorum sensing system affects biofilm development at increased salinity. To address this question we monitored morphology, growth, and biomass of the wild type and signal mutants in/on MSgg medium with different NaCl concentrations (0, 2, 4, 6 % (w/V)). We used different quorum sensing and quorum sensing response mutants: ∆comQ, ∆comP, ∆comA, ∆srfA, and ∆comQ ∆srfA. We also monitored viscosity of the wild type and mutants comQ, srfA and comQ srfA. Moreover, we evaluated epsA expression in the wild type and comQ mutant. The results indicate that increased salinity negatively affects pellicle development and colony growth of the wild type. It also decreases biomass, viscosity and wrinkling of both biofilm types, a colony and a pellicle. ComQ and comP mutants develop biofilms faster than the wild type at all tested NaCl concentrations, whereas the development of biofilms of srfA, comQ srfA and comA mutants is similar or faster only at the increased salinity. Biofilm of mutants are more viscous than the wild type at all tested NaCl concentrations. However, the dynamics of epsA expression does not explain the increased biofilm viscosity. Based on the results we conclude that the ComQXPA quorum sensing system downmodulates the biofilm development of B. subtilis and it does so at all tested salinities.
Secondary keywords: biotechnology;quorom sensing;osmotic stress;biofilm development;biofilm morphology;biofilm viscosity;surfactin;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 2019-12-14
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Študij biotehnologije
Pages: XIII, 47 f., [21] f. pril.
ID: 10915120