Effect of mucins on phage-host interactions in Bacillus subtilis

Jakin Lazar, Jaka (author), Dragoš, Anna (mentor)

This thesis investigates the influence of mucins on phage and bacterial attachment, biofilm formation, and phage-bacteria interactions. The study focuses on Bacillus subtilis, a non-pathogenic bacterium commonly found in soil, plant rhizosphere and animal gut, and Vibrio anguillarum, a fish-pathogenic bacterium commonly found in marine environments. The experimental procedures encompassed a phage-attachment assay, confocal laser scanning microscopy, and flow cytometry, to determine phage and bacterial adherence to mucin-coated surfaces. Metabolic activity of attached bacterial cells was assessed through oxygen consumption rate measurements. The findings reveal that lytic Bacillus phages exhibited significantly greater attachment to mucin-coated surfaces in comparison to agar surfaces. Moreover, the attachment of B. subtilis and V. anguillarum cells increased on mucin-coated surfaces compared to non-coated surfaces. However, the attachment of V. anguillarum cells to mucin diminished in the presence of phages, in contrast to B. subtilis, where the positive effect of mucin on attachment persisted even when phages were present. Enhanced attachment to mucin was also supported by increased metabolic activity of surface-attached biomass, measured via oxygen consumption rates. Furthermore, B. subtilis biofilms formed on mucin-coated surfaces exhibited a more 3D complex structure compared to surfaces coated solely with phages, even in the presence of mucin. The work supports previous findings of Bacteriophage Adherence to Mucus (BAM) model, extending it new beneficial and pathogenic bacterial species. It also reveals that in different phage-host systems, mucins have different effects on phage-host interactions, which may have implications for phage therapies or probiotic treatments strategies.

• Language: English
• Keywords: phage-host interactions, bacteriophages, mucins, Bacillus subtilis
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Year: 2023
• PID: 20.500.12556/RUL-150426
• COBISS.SI-ID: 164979715
• Publication date in RUL: 17.09.2023

Secondary language

• Language: Slovenian
• Title: Vpliv mucinov na interakcije med bakteriofagi in gostiteljsko bakterijo Bacillus subtilis

Abstract

To delo raziskuje pritrjevanje fagov in bakterij na mucine, vpliv mucinov na tvorbo biofilma ter na interakcije med fagi in bakterijami. Študija se osredotoča na nepatogeno bakterijo Bacillus subtilis, ki jo običajno najdemo v zemlji, rastlinski rizosferi in živalskem črevesju, ter na bakterijo Vibrio anguillarum, ki je patogen rib in jo običajno najdemo v morju. Eksperimentalni postopki so vključevali test pritrjevanja fagov, konfokalno lasersko mikroskopijo in pretočno citometrijo, da bi določili pritrditev fagov in bakterij na površine, prekrite z mucini. Metabolna aktivnost pritrjenih bakterijskih celic je bila ocenjena z meritvami hitrosti porabe kisika. Rezultati so pokazali, da se litični Bacillus fagi v primerjavi s kontrolnimi površinami, bistveno bolj pritrjujejo na površine, prekrite z mucini. Poleg tega se je na površine, prekrite z mucini, v primerjavi z agarjem, povečala pritrditev celic B. subtilis in V. anguillarum. Vendar se je pritrjevanje celic V. anguillarum na mucin v prisotnosti fagov zmanjšalo, v nasprotju z bakterijo B. subtilis, kjer se je pozitivni učinek mucinov na pritrditev bakterije ohranil tudi ob prisotnosti fagov. Povišano pritrjevanje na mucine je bilo podprto tudi s povečano metabolno aktivnostjo pritrjene bakterijske biomase, merjeno s hitrostjo porabe kisika. Poleg tega so biofilmi B. subtilis, nastali na površinah, prevlečenih z mucini, imeli bolj kompleksno 3D-strukturo v primerjavi s površinami, prevlečenimi samo s fagi, tudi ob prisotnosti mucinov. Delo podpira prejšnje ugotovitve modela pritrjevanja bakteriofagov na mukus (BAM) in ga razširja na nove koristne in patogene bakterijske vrste. Razkriva tudi, da imajo mucini v različnih sistemih fag-gostitelj različne učinke na interakcije med fagom in gostiteljem, kar lahko vpliva na strategije zdravljenja s fagi ali probiotičnimi zdravili.

• Keywords: interakcije bakteriofagi-gostitelj, bakteriofagi, mucini, Bacillus subtilis