Hibrid promoter induction

The objective of this assay is to figure out whether bacteria that get colored in the presence of arsenic, reach saturation over time when induced with different arsenite concentrations and if the colour intensity is distinguishable between each other at naked eye. To achieve this E. Coli DH5alfa Bacteria harbouring a plasmid that encodes mRFP generator under arsenite promoter (([http://parts.igem.org/Part:Bba_K1106003 Bba_K1106003]), were grown with different arsenite concentration ( 0, 10, 50, 200 and 1000ppb). 1ml aliquots were taken every 12 hours and were centrifuged at 10.000rpm for 5 minutes. Pictures of the pellets were taken in order to compare colour difference at naked eye. mRFP fluorescence was also measured with a fluoremeter at X nm for excitation and X nm for emission.