Molecular method for detection of total coliforms in drinking water samples

Area of Science:

• Microbiology
• Molecular Biology
• Environmental Science

Background:

• Total coliforms are indicators of potential microbial contamination in potable water.
• Traditional culture-based methods for coliform detection have limitations in sensitivity and speed.
• Genetic variability within the total coliform group poses challenges for accurate detection.

Purpose of the Study:

• To evaluate the efficacy of PCR assays targeting lacZ, wecG, and 16S rRNA genes for detecting total coliforms in potable water.
• To compare the performance of these molecular assays against established culture-based methods (Colilert and MI agar).
• To assess the applicability of PCR-based methods for real-world water quality monitoring.

Main Methods:

• Bacterial concentration and recovery procedures were employed.
• Three distinct PCR assays (lacZ, wecG, 16S rRNA) were developed and utilized.
• Assays were validated using 147 diverse coliform strains and subsequently applied to 122 well water samples.

Main Results:

• PCR assays demonstrated higher detection rates for coliform strains compared to culture methods (up to 99.3% for 16S rRNA PCR).
• In well water samples, 16S rRNA PCR showed comparable performance to culture-based methods (80.3% vs. 79.5% positive).
• The lacZ and wecG PCR assays also showed significant, though varied, detection capabilities.

Conclusions:

• Molecular assays, particularly 16S rRNA PCR, are viable tools for detecting total coliforms in potable water.
• These PCR methods offer advantages in sensitivity and potentially speed over traditional techniques.
• The 16S rRNA assay, possibly combined with an Escherichia coli assay, presents a promising approach for drinking water quality assessment.