A sensitive fluorescence method for detection of E. Coli using rhodamine 6G dyeing

Area of Science:

• Analytical Chemistry
• Microbiology
• Biotechnology

Background:

• Accurate and rapid bacterial detection is crucial for public health and environmental monitoring.
• Existing methods for bacterial quantification can be time-consuming or require specialized equipment.
• Development of sensitive and cost-effective detection techniques is an ongoing research area.

Purpose of the Study:

• To develop a simple, rapid, and sensitive fluorescence-based method for quantifying bacterial concentrations.
• To utilize the electrostatic interaction between negatively charged bacteria and positively charged rhodamine 6G (Rh6G) dye for detection.
• To validate the method's efficacy in analyzing real-world samples such as water and drinking water.

Main Methods:

• Bacteria were incubated with rhodamine 6G (Rh6G) dye in a phosphate buffer solution (pH 7.4) to facilitate electrostatic interaction.
• Fluorescence spectroscopy was employed to measure the fluorescence intensity of the dyed bacteria at a peak emission of 552 nm.
• The method was applied to quantify concentrations of Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), and Staphylococcus aureus (S. aureus) in various sample matrices.

Main Results:

• A strong fluorescence peak at 552 nm was observed for dyed bacteria.
• Fluorescence intensity showed a direct linear correlation with bacterial concentrations across specified ranges for E. coli, B. subtilis, and S. aureus.
• Low detection limits were achieved: 3.2 × 10^4 cfu/mL for E. coli, 2.3 × 10^5 cfu/mL for B. subtilis, and 16 cfu/mL for S. aureus.
• After 12 h of culturing, a linear detection range of 2 to 88 cfu/mL for E. coli was established.

Conclusions:

• The developed Rh6G-based fluorescence method offers a simple, rapid, and sensitive approach for bacterial quantification.
• The method demonstrates effective application in the analysis of bacterial contamination in water and drinking samples.
• This technique holds potential for routine environmental and public health monitoring due to its sensitivity and ease of use.