Microbial communities in anaerobic dynamic membrane bioreactor for municipal wastewater treatment: Comparison of bulk sludge and cake layer

454 high-throughput pyrosequencing was employed to investigate microbial communities in bulk sludge (BS) and cake layer (CL) in an anaerobic dynamic membrane bioreactor (AnDMBR). Proteobacteria were the most dominant in the BS, while Bacteroidetes, Firmicutes and Spirochaetes were highly enriched in the CL, accounting for 57.6% of the total microbes. The main microbial groups in the CL were highly functionally organized. Bacteroides, Clostridia and Delta-proteobacteria were likely the pioneers for surface colonization on membranes in the AnDMBR.