To facilitate international collaboration and communication on research and education on global water microbiome studies, Global Water Microbiome Consortium was formed in 2014, which involves 70 research groups in different universities and organizations from different countries. Initially, we focused on Municipal Wastewater Microbiome Initiative (MWMI). The first sampling campaign has collected over 1210 activated sludge (AS) samples from 274 wastewater treatment plants (WWTPs) in 100 cities of 24 countries, covering Asia, Australia, Europe, North America, South America, and South Africa. These samples have been analyzed with amplicon sequencing of 16S rRNA gene for bacteria and archaea, ITS for fungi, and amoA gene for nitrifiers.  Although massive datasets were available, the following general observations were observed. First, theoretical modeling predicted that WWTPs harbor up to 1 billion (10<sup>9</sup>) bacterial species globally, which is less than soil and ocean, but larger than gut microbiomes. Second, a global core microbiome appears to exist in WWTPs but their composition is very diverse. Third, despite inhabiting a built environment, the diversity in AS bacterial communities exhibited a significant distance-decay relationship but no obvious latitudinal diversity patterns were observed. Fourth, the community composition was better explained by geographical distance rather than environmental variations, indicating the importance of dispersal limitation in community assembly, which was further confirmed by neutral model simulations. Fifth, organic carbon level seems to be the strongest predictor of bacterial diversity, which is consistent with resource-ratio hypothesis in ecology. Notably, among environmental factors, temperature is also important in shaping bacterial community composition. In addition, the eukaryotic communities differed significantly by countries in the majority of samples, which could reflect different process choices and indicate the prospects for sequencing-based biosensors in process monitoring.

Global wastewater microbiome: Diversity and biogeography

255th National Meeting (2018)

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