Aspergillus fumigatus enhances elastase production in Pseudomonas aeruginosa co-cultures

Med Mycol. 2015 Sep;53(7):645-55. doi: 10.1093/mmy/myv048. Epub 2015 Jul 10.


In the cystic fibrosis (CF) lung the presence of bacteria and fungi in the airways promotes an inflammatory response causing progressive lung damage, ultimately leading to high rates of morbidity and mortality. We hypothesized that polymicrobial interactions play an important role in promoting airway pathogenesis. We therefore examined the interplay between the most commonly isolated bacterial CF pathogen, Pseudomonas aeruginosa, and the most prevalent filamentous fungi, Aspergillus fumigatus, to test this. Co-culture experiments showed that in the presence of A. fumigatus the production of P. aeruginosa elastase was enhanced. This was confirmed by the presence of zones of clearance on Elastin-Congo Red (ECR) agar, which was identified as elastase by mass spectrometry. When P. aeruginosa were grown in a co-culture model with mature A. fumigatus biofilms, 60% of isolates produced significantly more elastase in the presence of the filamentous fungi than in its absence (P < .05). The expression of lasB also increased when P. aeruginosa isolates PA01 and PA14 were grown in co-culture with A. fumigatus. Supernatants from co-culture experiments were also significantly toxic to a human lung epithelial cell line (19-38% cell cytotoxicity) in comparison to supernatants from P. aeruginosa only cultures (P < .0001). Here we report that P. aeruginosa cytotoxic elastase is enhanced in the presence of the filamentous fungi A. fumigatus, suggesting that this may have a role to play in the damaging pathology associated with the lung tissue in this disease. This indicates that patients who have a co-colonisation with these two organisms may have a poorer prognosis.

Keywords: Aspergillus; Pseudomonas; biofilms; cystic fibrosis; elastase.

MeSH terms

  • Aspergillosis / microbiology
  • Aspergillus fumigatus / growth & development*
  • Aspergillus fumigatus / isolation & purification
  • Bacterial Proteins / biosynthesis*
  • Bacterial Proteins / metabolism*
  • Cell Line
  • Cell Survival / drug effects
  • Child
  • Child, Preschool
  • Culture Media / chemistry
  • Cystic Fibrosis / complications
  • Epithelial Cells / drug effects
  • Epithelial Cells / physiology
  • Gene Expression Profiling
  • Humans
  • Mass Spectrometry
  • Metalloendopeptidases / biosynthesis*
  • Metalloendopeptidases / metabolism*
  • Microbial Interactions*
  • Microbiological Techniques
  • Pseudomonas Infections / microbiology
  • Pseudomonas aeruginosa / enzymology*
  • Pseudomonas aeruginosa / growth & development*
  • Pseudomonas aeruginosa / isolation & purification


  • Bacterial Proteins
  • Culture Media
  • Metalloendopeptidases
  • pseudolysin, Pseudomonas aeruginosa