Presentation Information
[P04-517]Effects of Pseudomonas aeruginosa Filamentous Phages on Biofilm Formation
○Hina Urabe1, Ayaka Uehara1, Mio Unoki1, Nobuhiko Nomura2,3,4,5, Masanori Toyofuku2,3,5 (1. Grad. Sch. Life Environ. Sci., Univ. Tsukuba (Japan), 2. Fac. Life Environ. Sci., Univ. Tsukuba (Japan), 3. TIAR, Univ. Tsukuba (Japan), 4. TARA, Univ. Tsukuba (Japan), 5. MiCS, Univ. Tsukuba (Japan))
Keywords:
filamentous phage,biofilm,Pseudomonas aeruginosa,flow cell,prophage
Purpose
A phage is a virus that infects bacteria. When a phage genome is integrated into a bacterial chromosome, it is referred to as a prophage. Recent studies have revealed that filamentous phages (Pf; Pseudomonas filamentous phage) lysogenized in Pseudomonas aeruginosa can promote biofilm formation. Despite growing interest in phage–biofilm interactions, the mechanisms involved in Pf activation within biofilms remain poorly understood. This study focuses on a marine Pseudomonas aeruginosa isolate, Ocean−1187S, which harbors a filamentous prophage, Pf_Oc87B. Our previous work demonstrated that Pf_Oc87B is phylogenetically distinct from known Pf phages. Therefore, by investigating the functional role of Pf_Oc87B within the biofilm formed by Ocean−1187S, we aim to gain new insights into the impact of Pf phages on biofilm development.
Methods
The role of the filamentous phage Pf_Oc87B in biofilm formation was examined using Pseudomonas aeruginosa strains Ocean−1187S and Ocean−1187S ΔPf_Oc87B. Individual Pf_Oc87B genes were overexpressed in Ocean−1187S, and biofilms were cultivated in a flow cell to allow growth under continuous flow. To confirm the production of phage particles within the biofilm, infectious phage particles in the biofilm effluent were quantified by plaque assay using the effluent as culture supernatant. Biofilms were stained with SYTOX Green, a membrane−impermeable nucleic acid dye, and changes in biofilm morphology associated with the presence or absence of Pf phages were examined using a confocal microscope.
Results
Overexpression of specific Pf genes resulted in gene−dependent changes in phage particle yield; particle numbers increased for some genes and decreased for others. In a flow cell biofilm, phage particles were detected in the effluent from wild-type but not from ΔPf_Oc87B. Confocal microscopy analysis revealed that the proportion of SYTOX Green-stained cells was reduced in the ΔPf_Oc87B biofilm.
Discussion
These results suggest that Pf prophages form particles within the biofilm and influence the viability of cells in the biofilm, indicating an intrinsic relationship between the host bacterium and its resident prophages.
A phage is a virus that infects bacteria. When a phage genome is integrated into a bacterial chromosome, it is referred to as a prophage. Recent studies have revealed that filamentous phages (Pf; Pseudomonas filamentous phage) lysogenized in Pseudomonas aeruginosa can promote biofilm formation. Despite growing interest in phage–biofilm interactions, the mechanisms involved in Pf activation within biofilms remain poorly understood. This study focuses on a marine Pseudomonas aeruginosa isolate, Ocean−1187S, which harbors a filamentous prophage, Pf_Oc87B. Our previous work demonstrated that Pf_Oc87B is phylogenetically distinct from known Pf phages. Therefore, by investigating the functional role of Pf_Oc87B within the biofilm formed by Ocean−1187S, we aim to gain new insights into the impact of Pf phages on biofilm development.
Methods
The role of the filamentous phage Pf_Oc87B in biofilm formation was examined using Pseudomonas aeruginosa strains Ocean−1187S and Ocean−1187S ΔPf_Oc87B. Individual Pf_Oc87B genes were overexpressed in Ocean−1187S, and biofilms were cultivated in a flow cell to allow growth under continuous flow. To confirm the production of phage particles within the biofilm, infectious phage particles in the biofilm effluent were quantified by plaque assay using the effluent as culture supernatant. Biofilms were stained with SYTOX Green, a membrane−impermeable nucleic acid dye, and changes in biofilm morphology associated with the presence or absence of Pf phages were examined using a confocal microscope.
Results
Overexpression of specific Pf genes resulted in gene−dependent changes in phage particle yield; particle numbers increased for some genes and decreased for others. In a flow cell biofilm, phage particles were detected in the effluent from wild-type but not from ΔPf_Oc87B. Confocal microscopy analysis revealed that the proportion of SYTOX Green-stained cells was reduced in the ΔPf_Oc87B biofilm.
Discussion
These results suggest that Pf prophages form particles within the biofilm and influence the viability of cells in the biofilm, indicating an intrinsic relationship between the host bacterium and its resident prophages.
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