Rapid fluorometric quantification of bacterial cells using Redsafe nucleic acid stain

Area of Science:

• Microbiology
• Biotechnology

Background:

• Accurate cell counting is crucial in biology and medicine.
• Traditional Colony Forming Unit (CFU) enumeration is labor-intensive and prone to errors, especially at high cell densities.

Purpose of the Study:

• To introduce and evaluate a novel indirect cell counting method using the Redsafe fluorometric assay.
• To compare the efficacy of the Redsafe assay with the established MTT colorimetric assay for bacterial enumeration.

Main Methods:

• The Redsafe fluorometric assay, utilizing a DNA-binding fluorescent dye, was employed for cell counting in liquid medium.
• Performance was assessed by comparing Redsafe assay results with those from the MTT colorimetric assay.

Main Results:

• The Redsafe fluorometric assay demonstrated a threshold of 6×10(4) CFU/ml for LB-grown E. coli.
• The assay proved to be a rapid, cost-effective method for bacterial quantification with enhanced sensitivity.

Conclusions:

• The Redsafe fluorometric assay exhibited a 2-log-unit greater sensitivity for bacterial cell detection and enumeration compared to the MTT assay.
• This fluorometric approach offers a significant improvement in sensitivity and efficiency for bacterial quantification.