MiDAS: Field Guide to the Microbes of Activated Sludge


MIDAS is a central resource for information about the microbes in the engineered ecosystem of activated sludge and similar wastewater treatment systems, such as biofilms, granules and membrane-bioreactors. There are over 60 genera of organisms typically abundant (> 0.1%) in the community and a majority of these do not have closely-related cultured relatives. 

Nomenclature in the anarchy outside of the mainstream systematic bacteriological naming has led to considerable confusion; here we propose a provisional naming scheme for the genera in community that can be used as a reference point for linking the most updated naming (taxonomy) and sequence data with functional information about the in situ metabolism of microbes in this habitat.


The data is manually curated by a small team of experts so we invite contribution if you find an error or have something that you think should be in the database. You can also sign up for the mailing list to receive the latest news and updates.

General use cases

Genus/species X has been identified in my plant

  • Are they typical (core) organisms in activated sludge?
  • What function do they typically perform?
  • Are these organisms occassional (transient) organisms that may be problematic for plant operation?

I have filaments of morphology, eg. Eikelboom type 0092

  • Which taxonomic groups are these organisms likely to come from?

I am interested in a function in activated sludge

  • Which microbes are typically associated with this process?


Linking taxonomy and function

The in situ physiology of many organisms in the activated sludge ecosystem is extensively characterised, in part due to its amenability to in situ methods, such as microautoradiography (MAR) and stable-isotope probing (SIP). The ambition of the MiDAS field guide is to summarise all the knowledge about the distribution, ecology and diversity, and metabolism of the important organisms in the ecosystem.

The MIDAS name-function table begins this task.

The information will be expanded in the coming months to include detailed in situ substrate specificity profiles, and putative capabilites from genomic data.



Start browsing your microbes now!



27 October 2014
Check them out!

23 September 2014
new version coming soon!

28 April 2014
Welome to the new and improved MiDAS database. Read more..


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MiDAS: a field guide to the microbes of activated sludge by Aaron M. Saunders, Mads Albertsen, Per H. Nielsen is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.


MiDAS is a manual curation of the Silva database and is redistributed for non-commercial use only.


MiDAS is maintained by Marta Nierychlo, Simon J. McIlroy and Mads Albertsen