Furthermore, application of modern methods such as 16S rRNA gene sequencing, allows for high throughput sequencing of the entire community (giving 10,000–100,000 sequences per sample), providing details of the dynamics of most potentially relevant microbes present.
The recent publication of the online MiDAS database addresses this problem with a curated taxonomy for the abundant organisms of activated sludge systems, which allows for taxonomic assignment down to genus level for most organisms present. Such observations are of questionable value given the phenotypic diversity encompassed by the higher-level phylogenetic groupings. In addition, due to the incomplete taxonomic annotation of commonly applied databases, previous studies have in general discussed community dynamics at the phylum and class levels.
This suggests that the microbial population in bulk water will largely determine the community structure of the mature biofilm.Ī few studies have suggested the participation of members of the Proteobacteria in membrane fouling, however, only one of these was conducted using a full-scale system treating real wastewater. This study indicates that, although putative pioneer species appear, the biofilm became increasingly similar to the bulk community with time. As the biofilm matured the initially abundant betaproteobacterial genera Limnohabitans, Hydrogenophaga and Malikia were succeeded by filamentous Chloroflexi and Gordonia as the abundant species. In order to track the dynamics of the fouling process, we concurrently investigated the communities of the biofilm, MBR bulk sludge, and the conventional activated sludge system used to seed the MBR system over several weeks from start-up. To gain an insight into this important question, we applied 16S rRNA gene amplicon sequencing with a curated taxonomy and fluorescent in situ hybridization to monitor the community of a pilot-scale MBR carrying out enhanced biological nitrogen and phosphorus removal with municipal wastewater.
Formation of biofilms on the membrane surface is the suggested cause, yet little is known of the composition or dynamics of the microbial community responsible. Membrane fouling presents the greatest challenge to the application of membrane bioreactor (MBR) technology.
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