Our research illustrates that many of the interactions between microbes involve factors that are important for a microbe's ability to cause disease in humans. Thus, we can use microbe-microbe interaction systems to better understand the molecular mechanisms that underlie different aspects of the host-pathogen relationship. Much of our work focuses on Pseudomonas aeruginosa and Candida albicans, two important opportunistic human pathogens. Using tractable bacterial-fungal model systems with the bacterium Pseudomonas aeruginosa and the fungus Candida albicans, we have uncovered multiple ways in which these organisms alter the growth and behavior of each other. Our goals are to understand the mechanisms by which microbes change their behavior in the context of microbial communities and to determine how these changes affect their interactions with the human host, to examine microbial interactions as a way to gain insight into novel ways to control microbial pathogens, and to develop new ways to study microbe-microbe interactions.