Establishing a Biofilm Co-culture of Pseudomonas and Aspergillus for Metabolite Extraction.

Filamentous fungi and bacteria form mixed-species biofilms in nature and diverse clinical contexts (Frey-Klett et al., 2011; Peleg et al., 2010). The interactions between fungi and bacteria, often mediated by secreted metabolites, have important ramifications for the biology of the interacting partners (Frey-Klett et al., 2011). This is particularly true for the bacterium Pseudomonas aeruginosa (P. aeruginosa) and the fungus Aspergillus fumigatus (A. fumigatus) which often reside in the same niche such as lungs of cystic fibrosis (CF) patients. Some studies have reported that co-infection with P. aeruginosa and A. fumigatus could lead to a decrease in lung function relative to their respective single species infection (Amin et al., 2010; Peleg et al., 2010). Metabolite extraction and analysis allow for the characterization of specific microbial metabolites in the polymicrobial biofilm. This protocol describes how to prepare the Pseudomonas-Aspergillus co-culture biofilm on solid medium in preparation for metabolite extraction.