The built environment microbiota initially resembles the outdoors before human associated interventions drive development toward functionally specific communities

The microbiota of the built environment is linked to usage, materials and, perhaps most importantly, human health. Many studies have attempted to identify ways of modulating microbial communities within built environments to promote health. None have explored how these complex communities assemble initially, following construction of new built environments. This study used high-throughput targeted sequencing approaches to explore bacterial community acquisition and development in a single structure. Microbial sampling spanned from site identification, through the construction process to commissioning and use. Commissioning the building significantly reduced bacterial richness, diversity and community structure. Outdoor environments exhibited greater longitudinal community stability than indoor environments. Community flux in indoor environments was associated with human interventions driving environmental selection which increased in indoor environments following commissioning. A reduction in outdoor community influence on indoor microbiotas was also observed. Indoor communities became enriched with human associated genera such as Staphylococcus, Pseudomonas, and Klebsiella. These data represent the first to characterize the initial assembly of bacterial communities in built environments and will inform future studies aiming to modulate built environment microbiota.