Chemical Signaling Between Bacteria and Fungi

In addition to their role in communication within single-species bacterial and fungal populations, extracellular microbial signaling molecules can shape the relationships between microbial species. Studies with the bacterium Pseudomonas aeruginosa and the fungus Candida albicans, two species that are frequently found together in clinical settings, has revealed multiple bacterial-fungal signaling interactions. The effects of these interactions include impacts on the production of antimicrobial toxins, fungal morphology, biofilm formation, and even the synthesis of these same molecules that participate in these interactions. Interestingly, many bacterial-fungal interactions are most apparent when organisms are grown in surface-associated biofilm communities where less stable and poorly soluble molecules can exert their effects. These studies demonstrate the abundance of chemical interactions that will likely be revealed as we dissect the relationships within simple and complex microbial communities.