Bacterial community composition and functional potential associated with a variety of urban stormwater sources

Pathogens and chemical contaminants in stormwater are major environmental and public health concerns. Characterizing the variability in composition and bioremediation functions of the microbial community from different sources of stormwater will help with efforts to properly manage water after it rains. To improve understanding of the variability and composition of the microbial community in run-off from different sources, we sampled stormwater over time from an outfall and receiving stream, along with run-off from different locations (rooftop, roadway) to identify microbial components associated with these urban waters. Community composition was variable in space and time for water samples from the same source. Even with this variability, we found taxonomic and functional groups differentially distributed in water samples collected during wet or dry weather or collected from different sources. The differentially distributed taxonomic and functional groups represent the unique characteristics of the source, such as when communities are exposed to iron in pipe material from the outfall or hydrocarbons flushed from various surfaces during rain events. Additionally, fecal indicator sequences from Clostridiales and Bacteroidales taxa made up a larger fraction of the microbial community from water collected under dry conditions. Our work characterizes the variability in microbial community composition and functions from a variety of urban water sources, with specific attention to communities from sources where water might be collected or treated with green infrastructure systems (e.g. rain gardens or biofilters). This will aid our understanding of the impact of human activities in urban environments on the surrounding water system.