Rapid Detection of Gram-Positive and -Negative Bacteria in Water Samples Using Mannan-Binding Lectin-Based Visual...

Area of Science:

• Environmental Science
• Biotechnology
• Analytical Chemistry

Background:

• Waterborne bacterial infections pose a significant global health risk, necessitating rapid and precise detection methods.
• Mannan-binding lectin (MBL) possesses inherent capabilities to recognize pathogen-associated molecular patterns (PAMPs), offering a potential basis for novel diagnostic tools.

Purpose of the Study:

• To develop a visual biosensor for the on-site detection of both Gram-positive and Gram-negative bacteria in water samples.
• To utilize the MBL protein's recognition properties for a simple, colorimetric bacterial detection assay.

Main Methods:

• Immobilization of MBL protein onto blue carboxyl-functionalized polystyrene microparticles (PSM).
• A two-step visual assay involving sample incubation with MBL-PSM and calcium chloride, followed by ethanol addition to observe color change.
• Visual detection based on a binary color response (blue for presence, colorless for absence of bacteria).

Main Results:

• The MBL-PSM biosensor successfully detected Gram-negative bacteria (Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) and Gram-positive bacteria (Enterococcus faecalis, Staphylococcus aureus).
• The biosensor demonstrated a low detection limit of 10^1.5 CFU/ml for all tested bacteria.
• Effective detection of pathogens in real-world water samples from a treatment plant was confirmed, without requiring specialized instrumentation.

Conclusions:

• The developed visual biosensor offers a promising, on-site solution for detecting a broad spectrum of waterborne bacteria.
• The MBL-based assay provides a rapid, cost-effective, and instrument-free method for water quality monitoring.
• This technology has the potential to enhance public health by enabling timely identification of bacterial contamination in water sources.