Co-Operative Biofilm Interactions between Aspergillus fumigatus and Pseudomonas aeruginosa through Secreted Galactosaminogalactan Exopolysaccharide

Hanna Ostapska, François Le Mauff, Fabrice N. Gravelat, Brendan D. Snarr, Natalie C. Bamford, Jaime C. Van Loon, Geoffrey McKay, Dao Nguyen, P. Lynne Howell, Donald C. Sheppard (Lead / Corresponding author)

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Abstract

The mold Aspergillus fumigatus and bacterium Pseudomonas aeruginosa form biofilms in the airways of individuals with cystic fibrosis. Biofilm formation by A. fumigatus depends on the self-produced cationic exopolysaccharide galactosaminogalactan (GAG), while P. aeruginosa biofilms can contain the cationic exopolysaccharide Pel. GAG and Pel are rendered cationic by deacetylation mediated by either the secreted deacetylase Agd3 (A. fumigatus) or the periplasmic deacetylase PelA (P. aeruginosa). Given the similarities between these polymers, the potential for biofilm interactions between these organisms were investigated. P. aeruginosa were observed to adhere to A. fumigatus hyphae in a GAG-dependent manner and to GAG-coated coverslips of A. fumigatus biofilms. In biofilm adherence assays, incubation of P. aeruginosa with A. fumigatus culture supernatants containing de-N-acetylated GAG augmented the formation of adherent P. aeruginosa biofilms, increasing protection against killing by the antibiotic colistin. Fluorescence microscopy demonstrated incorporation of GAG within P. aeruginosa biofilms, suggesting that GAG can serve as an alternate biofilm exopolysaccharide for this bacterium. In contrast, Pel-containing bacterial culture supernatants only augmented the formation of adherent A. fumigatus biofilms when antifungal inhibitory molecules were removed. This study demonstrates biofilm interaction via exopolysaccharides as a potential mechanism of co-operation between these organisms in chronic lung disease.

Original languageEnglish
Article number336
Number of pages20
JournalJournal of Fungi
Volume8
Issue number4
Early online date24 Mar 2022
DOIs
Publication statusPublished - Apr 2022

Keywords

  • Aspergillus fumigatus
  • Pel
  • Pseudomonas aeruginosa
  • biofilm
  • co-operation
  • cystic fibrosis
  • exopolysaccharide
  • galactosaminogalactan (GAG)
  • interaction
  • resistance

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