Simple and Precise Counting of Viable Bacteria by Resazurin-Amplified Picoarray Detection

Area of Science:

• Microbiology
• Biotechnology
• Analytical Chemistry

Background:

• Accurate viable bacterial counting is crucial for food safety and clinical diagnostics.
• Existing methods like agar plating and microscopy have limitations in speed, complexity, and precision.
• Microfluidic devices offer potential but require further development for efficient bacterial detection.

Purpose of the Study:

• To introduce a novel, rapid, and precise method for counting viable bacteria.
• To overcome the limitations of current bacterial enumeration techniques.
• To provide a versatile platform for microbiological sample analysis.

Main Methods:

• Developed RAPiD (Resazurin-Amplified Picoarray Detection) utilizing Picoarray microfluidic devices.
• Employed vacuum-assisted loading and oil-driven digitization for single bacterium confinement in picoliter chambers.
• Incorporated AlamarBlue dye to detect microcolonies via fluorescence amplification.
• Expanded the method to a "multi-RAPiD" strategy for parallel sample titrations.

Main Results:

• Achieved stochastic confinement of single bacteria in picochambers in under 30 seconds.
• Enabled rapid detection of microcolonies using fluorescence microscopy.
• Quantified viable cells in E. coli and S. aureus samples with high precision in approximately 3 hours.
• Demonstrated parallel analysis of multiple titrations from a single sample.

Conclusions:

• RAPiD offers a significant advancement in viable bacterial counting, combining speed and precision.
• The method is adaptable for various microbiological applications, including food quality and clinical diagnostics.
• RAPiD presents a promising alternative to traditional bacterial enumeration techniques.