The microbial community of two lab-scaled anMBR sludge, biofilm, and effluent.. Meta-data analysis of anMBR

A meta-analysis of sludge (i.e., 72 samples) and biofilm (i.e., 52 samples) sampled from anaerobic membrane bioreactors (anMBR) operated at three different geographical regions was conducted. Predominant microbial community identification and multivariate analysis indicated that geographical origin and time were the main parameters accounting for differences in microbial community. However, this difference did not impact anMBR performance. We further identified two core microbial consortiums which always occurs in all sludge (23 genera) and biofilm (10 genera) samples, respectively. For sludge core microorganism, net growth rate (NGR) calculation indicated these 23 core genera could be distributed to three main groups (i.e., low relative abundance and NGR, high relative abundance with low NGR, high relative abundance or high NGR). Consistent positive correlation between bacterial genera were observed among those that exhibit either high relative abundance or high NGR (e.g. Methanobacterium with Syntrophorhabdus and Methanothrix with Geobacter). The anaerobic microbial consortium in both sludge and biofilm were largely affected by stochastic, random dispersal and migration processes (i.e., neutral assembly). However, Acinetobacter spp. and Methanobacterium spp. deviated from the neutral assembly and occurred consistently in higher frequency in the biofilm but in lower occurrence frequency in the anMBR permeate. Our results indicate that this neutral model fit revealed that biofilm core microorganisms were actively being maintained and selected for by biofilm and membrane, inferring plays important roles in biofilm formation.