Tryptophan-like fluorescence as a high-level screening tool for detecting microbial contamination in drinking water

Area of Science:

• Environmental Science
• Public Health
• Analytical Chemistry

Background:

• Regular drinking water quality monitoring is crucial for public health, especially in low-resource settings.
• Microbial contamination testing is essential for preventing waterborne diseases and achieving Sustainable Development Goal 6.
• Traditional monitoring methods require significant resources, labor, and consumables.

Purpose of the Study:

• To assess the suitability of tryptophan-like fluorescence (TLF) as a rapid drinking water quality monitoring tool.
• To compare TLF data with thermotolerant coliforms (TTCs) and hydrochemical parameters in rural Malawi.
• To evaluate TLF's potential as a screening tool for microbial contamination.

Main Methods:

• A nine-month water quality monitoring program in rural Malawi.
• Collection of a large temporal dataset (n=235) from five groundwater sources.
• Comparison of TLF data with thermotolerant coliforms (TTCs, E. coli) and inorganic hydrochemical parameters.

Main Results:

• TLF indicated broader contamination risks but showed lower sensitivity to short-term variability compared to TTCs.
• Elevated TLF correlated with increased dissolved organic carbon (DOC), suggesting a wider range of sources.
• TLF may signal conditions favorable for TTCs/E. coli persistence, but not necessarily an immediate public health risk.

Conclusions:

• TLF can function as a precautionary risk indicator and a high-level screening tool for initial assessment.
• Standardization of TLF values for different risk levels is needed for widespread adoption.
• The influence of DOC/HLF on TLF signals complicates direct correlation with TTCs or E. coli counts.