Invitrogen™ Bacteria Counting Kit, for flow cytometry

The Bacteria Counting Kit accurately enumerates bacteria by flow cytometry. The kit includes the SYTO™ BC dye, which is also available separately (Cat No. S34855), a high-affinity nucleic acid stain that easily penetrates both gram-negative and gram-positive bacteria, producing an exceptionally bright green-fluorescent signal. The kit also includes a calibrated suspension of polystyrene microspheres. Signals from both the stained bacteria and the beads are easily detected in the green fluorescence channel and can be distinguished on a plot of forward scatter versus fluorescence. The density of the bacteria in the sample can be determined from the ratio of bacterial signals to microsphere signals in the cytogram.

Any physiological buffer between pH 7.0–8.0, including PBS, can be used to dilute the SYTO dyes for the staining solution.