Measurement of Bacterial Gene Expression by Fluorescence Method

I measured induction of the acid response gene called rcsB fused downstream of lux promoter which encodes for GFP (green fluorescent protein) in rcsB knock out strain background using Fluoroskan Ascent FL microplate Fluorometer. After growing E. coli cells to OD 600 of 0.3 in 200 µl volume in a 96 microplate, the pH of the medium was brought down to 2.5 by titrating with 1 M HCl and then the inducer was added. After 20 minutes induction was noticed and appeared highest in 110 minutes. There was induction in the rcsB knock out strain with plasmid expressing rcsB-GFP under lux promoter induction in the absence of inducer.