Abstract
Microbes often live in multispecies communities where interactions among community members impact both the individual constituents and the surrounding environment. Here, we developed a system to visualize interspecies behaviors at initial encounters. By imaging two prevalent pathogens known to be coisolated from chronic illnesses, Pseudomonas aeruginosa and Staphylococcus aureus, we observed P. aeruginosa can modify surface motility in response to secreted factors from S. aureus. Upon sensing S. aureus, P. aeruginosa transitioned from collective to single-cell motility with an associated increase in speed and directedness - a behavior we refer to as 'exploratory motility'. Explorer cells moved preferentially towards S. aureus and invaded S. aureus colonies through the action of the type IV pili. These studies reveal previously undescribed motility behaviors and lend insight into how P. aeruginosa senses and responds to other species. Identifying strategies to harness these interactions may open avenues for new antimicrobial strategies.