Defining mechanisms of fungal-bacterial interactions during infection

Project Summary Aspergillus fumigatus (Af) is the most common and life-threatening airborne opportunistic fungal pathogen. Investigations into Af pathogenesis have focused primarily on mono-species infections. The impact of co- infecting microbes on Af physiology during infection remains an understudied but critically important research area. Using cystic fibrosis (CF) infection as a model, my recent work has focused on characterizing Af physiology in the presence and absence of the coinfecting bacterial pathogen, Pseudomonas aeruginosa (Pa), using multi- omics approaches combined with reverse genetics. I have uncovered two major mechanisms of Af and Pa interkingdom communication, mediated through the toxic, microbial secondary metabolites gliotoxin (produced by Af) and hydrogen cyanide (produced by Pa). The proposed project builds logically on this work and aims to uncover the mechanistic basis underlying the physiological shifts which occur in both organisms upon coculture in synthetic CF sputum media. This work will also test if clinical isolates of Af and Pa maintain these secondary metabolite response networks after chronic human infection and test to what extent polymicrobial interactions impact Af physiology during human infection using advanced sequencing technologies. The overall goal of this application is two-fold: 1) to define the specific molecular basis for interactions that occur between Af and Pa (Specific Aim 1); and 2) to expand on these findings to determine the impact of microbial interactions and the host environment on Af physiology during human CF infection (Specific Aim 2). This work is likely to yield important discoveries that will aid in our understanding of both fungal physiology and the underlying mechanisms of interkingdom microbial interactions within chronic polymicrobial infections.