OOS 23-1 - Buildings as habitats and sinks for fungi: Resolving the sources of the fungi we live and work with

Wednesday, August 8, 2012: 8:00 AM
C124, Oregon Convention Center
Adams, Rachel Adams, Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA and Thomas D. Bruns, Department of Plant and Microbial Biology, University of California, Berkeley, CA

Fungal spores and hyphal fragments are common components of the air inside buildings, and they can have adverse impacts on human health.  Much of the early work on indoor fungi focused on those that are readily cultured and easily identified by their morphology; such work revealed a relatively small set of common genera.  In contrast, recent high-throughput sequence approaches reveal a much greater fungal diversity in buildings, but many of the taxa found were clearly derived from outdoor environments.  Concordant with their outdoor origin, the global pattern of occurrence of fungi found in buildings suggests that climate and dispersal limitation are more important drivers than building type or occupancy. The emerging model, then, is that most fungal biomass indoors is derived from the outdoor environment with a more limited set of taxa that grow or are enriched in the built environment. To test this model, we have set up an experiment relying on replicated samples, within two-month time windows in residential buildings to survey the indoor air for fungal material, as well as to sample possible sources of fungi, including the outdoor air and moist habitats indoors.  We also have taken samples across years in a classroom laboratory to examine the residence time for the detection of fungal sequences. 


At this point we know that our methods are working, and that fungal sequences we retrieve at shorter time-window are diverse and include those seen in longer time samples of accumulated dust.  We also found that DNA of some fungi appears to lie resident, possibly as viable propagules, for longer periods of time.  These results are concordant with our model, and suggest that the time window analyzed is an important parameter. Our study further elucidates how dispersal, turnover, and source-sink dynamics interact to shape the environment in which we typically spend 90% of our time.