MycoLight™ Red JJ94 *2.5 mM in DMSO*

Green fluorescent protein (GFP) derivatives are widely used as fluorescent reporters to study biological processes at the cellular and molecular level, including labeling bacteria. Unfortunately, the GFP-based bacterial labeling is tedious, and several important organisms have remained difficult to modify for fluorescent protein expression. Complimentary to GFP-based fluorescence labeling of bacteria, SYTO-9 has been widely used for labeling bacteria in a more convenient mode, i.e., through a simple incubation. However, SYTO-9 is reported to significantly inhibit some bacterial growth. AAT Bioquest has developed MycoLight™ Red JJ94 that has minimal inhibition of bacterial growth compared to SYTO-9. In addition, MycoLight™ Red JJ94 can be used for multicolor detection of bacteria with the widely used GFP probes. It has an excitation and emission at ~637 and ~651 nm, respectively. This perfectly matches the He-laser excitation and Cy5 filter set that are commonly equipped in most fluorescence microscopes and flow cytometers. MycoLight™ Red JJ94 is a far-red fluorescent DNA-binding dye for straightforward live bacterial cell labeling, allowing subsequent infection studies. It has low intrinsic fluorescence, but upon binding DNA, its fluorescence emission intensity increases dramatically. MycoLight™ Red JJ94 readily stains live bacteria without compromising microbial growth. Under the same conditions, SYTO-9 inhibits bacterial growth substantially while MycoLight™ Red JJ94 is fully compatible with normal bacterial growth in liquid medium or on solid medium. The bacterial fluorescence labeling by MycoLight™ Red JJ94 is stable over several hours after shifting the bacteria into dye-free media.