magistrsko delo
Ana Grosek (Author), Anja Klančnik (Reviewer), Tjaša Danevčič (Mentor), Eva Kovačec (Co-mentor)

Abstract

V magistrskem delu smo raziskovali molekularne mehanizme, ki vodijo interakcije med bakterijama Bacillus subtilis in Salmonella enterica. Mikrobne interakcije so lahko kooperativne (prinašajo koristi obema partnerjema) ali kompetitivne (prinašajo koristi eni in škodujejo drugi bakteriji). Kompeticija je še posebej intenzivna v mešanih biofilmih. Za testiranje delovanja specifičnih komponent biofilma bakterije S. enterica v interakciji z bakterijo B. subtilis smo uporabili različne mutante bakterije S. enterica z inaktiviranim genom glavnega regulatorja za tvorbo biofilma (ΔcsgD), genom za sintezo celuloze (⠆bcsA) in genom za sintezo fimbrij (⠆csgB). Uporabljenim sevom smo najprej določili površinske značilnosti, to so avtoagregacija, koagregacija in hidrofobnost površine. Nato smo spremljali kompetitivne interakcije v tekočem gojišču pri različnih okoljskih pogojih in analizirali posledice sogojenja specifičnih mutant bakterije S. enterica z bakterijo B. subtilis v mešanih biofilmih. Ugotovili smo, da ima pomanjkanje hranil večji vpliv na kompeticijo pri višjih temperaturah, kot pri nižjih temperaturah, ter da se adhezija bakterije S. enterica ob prisotnosti bakterije B. subtilis zmanjša. Preučili smo tudi občutljivost enovrstnih in mešanih biofilmov na različne antibiotike in jim določili minimalne inhibitorne koncentracije. Občutljivost bakterije S. enterica se je v kokulturi z bakterijo B. subtilis najbolj povečala v primeru dodatka antibiotika tetraciklina. Iz rezultatov smo zaključili, da je potencialni probiotični sev B. subtilis PS-216 primeren kandidat za dodajanje ob zdravljenju okužb z bakterijo S. enterica, saj le-ta poveča občutljivost patogene bakterije na antibiotik tetraciklin.

Keywords

mešani biofilmi;Salmonella enterica;Bacillus subtilis;kompetitivne interakcije;probiotiki;odpornost proti antibiotikom;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [A. Grosek]
UDC: 579.22/.26:577.2
COBISS: 144932355 Link will open in a new window
Views: 608
Downloads: 0
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Other data

Secondary language: English
Secondary title: Molecular mechanisms and consequences of interactions in Bacillus and Salmonella mixed biofilms
Secondary abstract: In this master’s thesis, we investigated the molecular mechanisms controlling interactions between Bacillus subtilis and Salmonella enterica. Microbial interactions can be cooperative (beneficial to both partners) or competitive (beneficial to one and detrimental to the other). Competition is especially strong in multi-species biofilms. To test the role of specific biofilm components of S. enterica in the interaction with B. subtilis, we used different mutants of S. enterica with inactivated biofilm production master regulatory gene (ΔcsgD), cellulose synthesis gene (⠆bcsA), and fimbriae synthesis gene (⠆csgB). First, we determined the surface properties of the strains used, i.e. auto-aggregation, co-aggregation and hydrophobicity. Then we observed the competitive interaction in a liquid medium under different environmental conditions, and analysed the consequences of co-culturing of specific mutants of S. enterica with B. subtilis in mixed biofilms. We found that nutrient deficiency affects competition more at higher temperatures than at lower temperatures and that S. enterica adhesion decreases in the presence of B. subtilis. We also investigated the susceptibility of mono-species and multi-species biofilms to various antibiotics and determined the minimal inhibitory concentration. The susceptibility of S. enterica in co-culture with B. subtilis increased most with the addition of the antibiotic tetracycline. From the results, we concluded that the potential probiotic strain B. subtilis PS-216 is a suitable candidate in the treatment of S. enterica infections, because it increases the susceptibility of pathogenic bacteria to the antibiotic tetracycline.
Secondary keywords: mixed species biofilm;Salmonella enterica;Bacillus subtilis;competitive interactions;probiotics;antibiotic resistance;
Type (COBISS): Master's thesis/paper
Study programme: 0
Embargo end date (OpenAIRE): 2025-03-09
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za mikrobiologijo
Pages: 1 spletni vir (1 datoteka PDF (XII, 66 str., [5] f. pril.))
ID: 18241767