Recent field investigations of the microbiology of the built environment have demonstrated that the biological composition of indoor air and building surfaces is vastly more complex than previously thought. Very little is known, however, about the fundamental ecology of the microbes that colonize these locations. This grant supports efforts by a research team led by Jack Gilbert, associate professor in the Department of Ecology and Evolution at the University of Chicago, to develop new knowledge about the metabolism of indoor microbial communities using experimental and modeling approaches. The team plans to examine how different building surface materials, under variable temperature and humidity conditions, influence microbial growth, evolution, and survival and will develop a mechanistic model that can predict the succession and metabolism of microbial communities on surfaces. Dr. Gilbert and his team will seed tile, laminate, wood, and metal surfaces with defined microbial consortia acquired from human skin, dog fur, and soil, and observe microbial community succession under various temperature and humidity conditions. Their observations will test a number of important hypotheses, including how humidity affects the diversity of metabolically active bacteria and fungi, whether taxonomic diversity of active microbes decreases over time, how air temperature affects cell grow rates, and how the bacteria-to-phage ratio in a given microbial community affects overall community size.   If successful, the project will result in new knowledge about bacterial succession in the built environment and provide a mechanistic model to improve understanding of the metabolic activities of indoor microbes. The team plans to share their findings through publications in peer-reviewed journals, presentations at meetings and conferences, and through the use of social and traditional media. At least two postdoctoral fellows and two graduate students will be trained.