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From 2011.igem.org

E. coli Nissle 1917 - A novel biofilm-forming chassis

When the team began thinking about our project in May, we decided that it would be interesting to work with biofilm forming bacteria, however, we encountered several problems before we were able to start measuring the effect of our biobricks.

Firstly, we needed a repeatable method through which to form biofilms. As research in this area is relatively new, there are a large number of proposed methods available for growing biofilm. Unfortunately, many required specialised materials which we did not have access to or were prohibitively expensive. In the end, we developed a new protocol for growing biofilm based on a number of other protocols and the materials that we had available to us in the lab.

Next we required an assay through which to measure biofilm formation and dispersal. This required not only qualitative measurements (ie - has any biofilm formed at all?) but also in a manner which generates quantitative results. Again, other methods for this do already exist but were inaccessible to us because of cost or availability - because of this we generated a method for measuring formation and dispersal using the materials that we had available.

When we came to actually attempting to form biofilm we encountered another problem: many of the lab strains of E. coli have selectively lost their ability to form biofilm due to chromosomal deletions. We considered using alternative organisms to form biofilm but decided against this path as a majority of the biobricks available in the registry have already been optimised for use in E. coli. Whilst researching different strains of E. coli with the ability to form biofilm a member of our team came across the Nissle 1917 strain. It has previously been documented on multiple occasions to be safe for human consumption and is commercially available as Mutaflor tablets in Germany.