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Molecular Viability Testing of UV-Inactivated Bacteria
Kris M Weigel1, Felicia K Nguyen1, Moira R Kearney1
1Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, USA.
Applied and Environmental Microbiology
|March 12, 2017
Summary
Molecular viability testing (MVT) accurately distinguishes live bacteria from dead ones after UV disinfection. This PCR-based method detects bacterial rRNA precursor synthesis, overcoming limitations of DNA-based detection for effective microbial inactivation assessment.
Area of Science:
- Microbiology
- Molecular Biology
- Environmental Science
Background:
- Standard PCR detects bacterial DNA but cannot differentiate live cells from dead cells or free DNA.
- Existing methods struggle to confirm the efficacy of disinfection processes like UV irradiation.
- Accurate viability assessment is crucial for ensuring the safety of disinfected water, food, and materials.
Purpose of the Study:
- To evaluate Molecular Viability Testing (MVT) for assessing bacterial inactivation by UV irradiation.
- To compare MVT with viability PCR (vPCR) in detecting UV-inactivated bacteria.
- To demonstrate MVT's ability to distinguish viable from non-viable bacterial cells post-UV treatment.
Main Methods:
- Molecular Viability Testing (MVT) was used, correlating viability with rRNA precursor synthesis after nutritional stimulation.
- Bacterial strains including Escherichia coli, Aeromonas hydrophila, and Enterococcus faecalis were subjected to UV irradiation.
- Viability PCR (vPCR), based on cell envelope integrity, was used as a comparative method.
Main Results:
- MVT successfully detected the inactivation of E. coli, A. hydrophila, and E. faecalis by UV irradiation.
- Some UV-inactivated E. coli cells showed transient pre-rRNA synthesis, leading to potential false positives within 1 hour.
- MVT consistently identified viable but culture-undetectable E. coli cells.
- Viability PCR (vPCR) failed to distinguish between viable and UV-inactivated bacteria in certain conditions.
Conclusions:
- Molecular Viability Testing (MVT) is a promising method for rapidly assessing microbial inactivation by UV treatment.
- MVT offers a significant advantage over DNA-based methods by distinguishing live from dead cells.
- This technique can improve the reliability of disinfection efficacy confirmation in various applications.
