Urban microbial ecology is an emerging field that will impact how we build our cities and maintain clean water. We were one the first labs to sequence the microbiome of urban sewer infrastructure, which lead us to describe a high abundance of resident organisms within pipes. Members of this pipe community are likely excellent models to understand basic questions of how microbes adapt to new environments since modern sewer systems have only existed for a few hundred years.  We collaborate closely with A. Murat Eren (University of Chicago) and Ryan Newton (University of Wisconsin-Milwaukee), to explore the selective pressures and unique niche these organisms occupy the thousands of miles of pipes within cities. This community is relatively simple and dominated by organisms such as Arcobacter and Acinetobacter; they account for nearly 70% of the microbes in untreated sewage and are released into the environment at high densities during sewage overflows or because of failing infrastructure. Microbiome work in this context has only recently gained attention, but is potentially very important. The organisms resident to the pipes could play an important role in the cycling of nutrients, and degradation of pathogens and chemicals within the conveyance system.

Research Tidbit

Arcobacter is a minor member (<0.01%) of the human fecal microbiome; however, qPCR showed that sewage influent contained >2 orders of magnitude higher abundance than human-associated fecal indicators, suggesting selective survival and growth within the sewer systems. Oligotyping revealed that the dominant phylotype in humans was also the dominant phylotype in sanitary sewers and fecal- or sewage-contaminated aquatic samples. Certain strains (e.g., A. butzleri) have been classified as emerging pathogens because of their association with gastroenteritis and even bacteremia.  Further investigation into the extent of virulence potential in this genus is needed to determine the risk associated with the presence and persistence of these organisms in sewage-contaminated waters.

This research was funded by a National Institutes of Health Grant to SLM (1R01-AI091829)