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From 2014.igem.org

Azo-dye toxicity test

The main purpose of this project is to create an azo-dye degrading device that could potentially be used in an industrial context in order to detoxify and decolourise textile and cosmetic industry wastewater. In order to test the viability of E. coli cells in azo-dye contaminated water, their growth was analysed at different concentrations of two chosen dyes; Reactive Black 5 (RB5) and Acid Orange 7 (AO7). The cells were grown overnight at 37 ºC and 250rpms, and the OD was measured at 680nm (wavelength that interferes with dyes as least as possible) at late exponential - stationary phase. The protocol for this experiment can be found here.

The results of this assay show that the tested azo-dyes are not toxic to E. coli at the conditions and concentrations of the experiment. This means that E. coli could be a suitable candidate for bioreactor-setting degradation of water effluents with high concentrations of azo-dyes.