Vital Staining of Bacteria by Sunset Yellow Pigment

In this study, we describe a method for discriminating pathogenic bacteria with a dye. First, we determined that among several colours tested, the sunset yellow pigment easily coloured Escherichia coli bacteria yellow. Next, we demonstrated that E. coli O157:H7, Shigella flexneri O301, Staphylococcus aureus and Bacillus subtilis could all be well marked by sunset yellow pigment. Finally, we performed bacterial viability assays and found there was no effect on bacterial growth when in co-culture with sunset yellow. Our results suggest that sunset yellow is suitable pigment to dye microorganisms.