Long-term microbial community dynamics in a pilot-scale gas sparged anaerobic membrane bioreactor treating municipal wastewater under seasonal variations.

•Long-term (472 days) microbial dynamics in a pilot Anaerobic membrane bioreactor.•AnMBR microbial community resilient to ambient temperature (14–27 °C) operation.•No shift in core microbiome due to influent wastewater microbial community.•Acetoclastic methanogenesis was predominant and unaffected by seasonal changes.•Evidence of syntrophic interactions and proliferation of sulfate reducing bacteria.