Erythrosin B: A versatile colorimetric and fluorescent vital dye for bacteria

Abstract

Rapidly assaying cell viability for diverse bacteria species is not always straightforward. In eukaryotes, cell viability is often determined using colorimetric dyes; however, such dyes have not been identified for bacteria. We screened different dyes and found that erythrosin B (EB), a visibly red dye with fluorescent properties, functions as a vital dye for many Gram-positive and -negative bacteria. EB worked at a similar concentration for all bacteria studied and incubations were as short as 5 min. Given EB's spectral properties, diverse experimental approaches are possible to rapidly visualize and/or quantitate dead bacterial cells in a population. As the first broadly applicable colorimetric viability dye for bacteria, EB provides a cost-effective alternative for researchers in academia and industry. METHOD SUMMARY Incubation of erythrosin B with bacteria specifically stains membrane-compromised dead cells. Live and dead cells can then be quantified via bright-field microscopy or any number of instruments that quantitate fluorescence.