<i>Aspergillus fumigatus</i> secondary metabolite pyripyropene is important for the dual biofilm formation with <i>Pseudomonas aeruginosa</i>

The human pathogenic fungus <i>Aspergillus fumigatus</i> establishes dual biofilm interactions in the lungs with the pathogenic bacterium <i>Pseudomonas aeruginosa</i>. Screening of 21 <i>A</i>. <i>fumigatus</i> null mutants revealed seven mutants (two G protein-coupled receptors, three mitogen-activated protein kinase receptors, a Gα protein, and one histidine kinase receptor) with reduced biofilm formation, specifically in the presence of <i>P. aeruginosa</i>. Transcriptional profiling and metabolomics analysis of secondary metabolites produced by one of these mutants, Δ<i>gpaB</i> (<i>gpaB</i> encodes a Gα protein), showed GpaB controls the production of several important metabolites for the dual biofilm interaction, including pyripyropene A, a potent inhibitor of mammalian acyl-CoA cholesterol acyltransferase. Deletion of <i>pyr2</i>, encoding a non-reducing polyketide synthase essential for pyripyropene biosynthesis, showed reduced <i>A. fumigatus</i> Δ<i>pyr2-P. aeruginosa</i> biofilm growth, altered macrophage responses, and attenuated mouse virulence in a chemotherapeutic murine model. We identified pyripyropene as a novel player in the ecology and pathogenic interactions of this important human fungal pathogen.IMPORTANCE<i>Aspergillus fumigatus</i> and <i>Pseudomonas aeruginosa</i> are two important human pathogens. Both organisms establish biofilm interactions in patients affected with chronic lung pulmonary infections, such as cystic fibrosis (CF) and chronic obstructive pulmonary disease. Colonization with <i>A. fumigatus</i> is associated with an increased risk of <i>P. aeruginosa</i> colonization in CF patients, and disease prognosis is poor when both pathogens are present. Here, we identified <i>A. fumigatus</i> genetic determinants important for the establishment of <i>in vitro</i> dual <i>A. fumigatus-P. aeruginosa</i> biofilm interactions. Among them, an <i>A. fumigatus</i> Gα protein GpaB is important for this interaction controlling the production of the secondary metabolite pyripyropene. We demonstrate that the lack of pyripyropene production decreases the dual biofilm interaction between the two species as well as the virulence of <i>A. fumigatus</i> in a chemotherapeutic murine model of aspergillosis. These results reveal a complete novel role for this secondary metabolite in the ecology and pathogenic interactions of this important human fungal pathogen.