This study aimed to investigate the effect of Brilliant Blue and Dark Green food dyes on the Escherichia coli which is part of the intestinal flora.The food dye stock solution was prepared as 50 mg/ml with serum physiologic solution. Both of the food dyes were added in nutrient broth medium as 5, 2,5 and 1,25 mg/ml concentrations Design bacteria was inoculated inside of the dyes a 0.34 McFarland. After samples werewaitedin shaking incubator during 24 h, streaking was made to agar medium. In addition, RNA of control and sample groups were extracted forusing kits for molecular studying. Isolated RNAs were exposed to real time PCR (polimerase chain reaction) to determine whether or not to be mutation at lacZ gene region of chromosome. That was the result of the study which has been found that bacteria growth decreased in bacteria groupsapplied Brilliant Blue and Dark Green compared to control group especially after 12th day. More and more raising of Brilliant Blue and Dark Green concentration prevented E. coli growth. Real time PCR results indicate that both of two food dyes have toxicity on E. coli generations were not related to lacZ gene mutation. When effects of Dark Green and Brilliant Blue on growth of E. Coli ATCC 10799 strain for 20 generations, a general reduction has been observed in bacterial reproduction in all 3 doses, from the 1st day to the 20th day. While fluctuations existed in the number of bacterial colonies from the 1st day until the 12th day, as of 12th day there is a stable reduction. It has been understood whether the reason of this phenotypic reduction is genotypic or not.
