A Chemostat-Based Model for Growing Bacterial Biofilms

ABSTRACT Biofilms are groups of microbes that live together in dense communities, often attached to a surface. They play an outsized role in all aspects of microbial life, from chronic infections to biofouling to dental decay. In recent decades, appreciation for the diversity of roles that biofilms play in the environment has grown. Yet, most bacterial studies still rely upon approaches developed in the 19 th century and center on planktonic populations alone. Here we present a chemostat-based experimental platform to investigate not only biofilms themselves, but how they interact with their surrounding environments. Our results show that biofilms grow to larger sizes in chemostats as opposed to flasks. In addition, we show that biofilms may be a consistent source of migrants into planktonic populations. We also show that secondary biofilms rapidly develop, although these may be more susceptible to environmental conditions. Taken together, our data suggest that chemostats may be a flexible and insightful platform for the study of biofilms in vitro . IMPORTANCE Biofilms are the predominant way that bacteria live in natural environments and are characterized by three emergent properties: ubiquity, resilience, and impact. They can be found across all environments, both natural and human-made, and across all of recorded time, dating back at least 3.5 billion years. Biofilms also represent a major economic impact of over $5 trillion annually. Yet, most of what is known about bacteria is the result of studies using planktonically growing liquid cultures under laboratory conditions. Here, we propose a comprehensive experimental platform that allows for study of biofilms on the molecular, organismal, and community levels using chemostats.