The fungal pathogen is frequently cultured from the sputum of cystic fibrosis (CF) patients along with the bacterium secretes a range of secondary metabolites, and one of these, gliotoxin, has inhibitory effects on the host immune response. The effect of culture filtrate (CuF) on fungal growth and gliotoxin production was investigated. Exposure of hyphae to cells induced increased production of gliotoxin and a decrease in fungal growth. In contrast, exposure of hyphae to CuF led to increased growth and decreased gliotoxin production. Quantitative proteomic analysis was used to characterize the proteomic response of upon exposure to CuF. Changes in the profile of proteins involved in secondary metabolite biosynthesis (e.g. gliotoxin, fumagillin, pseurotin A), and changes to the abundance of proteins involved in oxidative stress (e.g. formate dehydrogenase) and detoxification (e.g. thioredoxin reductase) were observed, indicating that the bacterial secretome had a profound effect on the fungal proteome. Alterations in the abundance of proteins involved in detoxification and oxidative stress highlight the ability of to differentially regulate protein synthesis in response to environmental stresses imposed by competitors such as . Such responses may ultimately have serious detrimental effects on the host.