Toward Proactive Water Quality Monitoring: Integrating Molecular and Chemical Approaches for Detection of Cyanobacterial Toxins and Genetic Markers

Drinking Water
Poster Presentation

Prepared by M. Rashedan
Los Angeles Department of Water and Power, 967 E Colorado Blvd., Unit 60042, Pasadena, CA, 91116, United States


Contact Information: [email protected]; 213-367-8476

ABSTRACT

Abstract:
Background:
Cyanobacterial harmful algal blooms (CyanoHABs) pose an increasing threat to freshwater resources globally. These blooms can produce a range of potent toxins, which threaten ecological health and drinking water safety. Detecting these toxins early, especially in remote and untreated water sources, is critical for proactive water quality management.

Methods:
This study applied an integrated monitoring approach combining molecular diagnostics and chemical analysis to assess cyanotoxin risk.

Results:
The qPCR assays demonstrated widespread detection of toxin-producing gene markers, with microcystin genes being the most frequently observed. However, gene presence did not always correlate with measurable toxin concentrations. ELISA testing revealed a variable distribution of total MC/NOD levels, with a significant number of samples exhibiting detectable or elevated
concentrations.
Congener analysis revealed the presence of multiple microcystin variants, with MC-LR, being the most commonly detected. Notably, samples with high total microcystin concentrations frequently showed multiple congeners, suggesting complex bloom dynamics and potential health risks.

Discussion:
The combination of molecular and chemical testing allowed for comprehensive monitoring of both toxin potential and actual toxin presence. While molecular assays are valuable for early detection and understanding bloom potential, they must be interpreted alongside chemical toxin data to assess real-time risk.
This study highlights the importance of an integrated monitoring framework, particularly in remote areas where conventional surveillance is logistically challenging. The findings support the use of gene-based assays as an early-warning tool but reinforce the need for confirmatory chemical analysis—especially when informing public health or water treatment decisions.

Conclusion:
An integrated molecular-chemical approach provides a robust and scalable solution for cyanotoxin surveillance in remote source waters. Monitoring both gene markers and actual toxin levels enables better-informed risk assessments and more effective management of cyanobacterial threats to raw water quality.

Presentation Description:

A Multi-Tiered Approach to Monitoring Cyanotoxins Using Integrated Molecular and Chemical Methods: The increasing prevalence of cyanobacterial harmful algal blooms (HABs) in freshwater ecosystems poses significant risks to water quality and public health, especially in remote raw water sources that often lack routine monitoring. To address this challenge, we employed a comprehensive, multi-tiered monitoring strategy that integrates cutting-edge molecular and chemical analytical techniques for the detection and quantification of key cyanotoxins and their genetic markers.

Central to this approach was the utilization of the Phytoxigene quantitative polymerase chain reaction (qPCR) platform, which enabled sensitive and specific quantification of toxin-producing gene markers associated with major cyanotoxins—microcystins, saxitoxin, and cylindrospermopsin. This molecular-level detection provides early insight into the presence and potential toxicity of cyanobacterial populations before toxins reach harmful concentrations.
Complementing the molecular analysis, parallel enzyme-linked immunosorbent assay (ELISA) testing was conducted to measure the total concentrations of microcystins and nodularin in water samples. ELISA serves as a robust, widely validated chemical assay to confirm and quantify actual toxin levels, ensuring the detection of biologically active compounds relevant to health risk assessments.
For samples exhibiting detectable toxin levels, we applied advanced congener-specific analysis techniques to delineate individual microcystin variants present. This congener profiling is crucial, as different microcystin variants vary widely in toxicity and environmental persistence. Identifying the specific congener profile allows for more accurate risk characterization and tailored management responses.

Over an extended monitoring period, temporal trends in both gene marker presence and toxin concentrations were systematically evaluated. This longitudinal assessment provided critical insights into bloom dynamics, toxin production cycles, and environmental factors influencing cyanotoxin risks. The combined molecular and chemical data sets reinforced the value of integrated monitoring strategies, highlighting their superior sensitivity and predictive capability compared to single-method approaches.

The results of this study contribute substantially to the development of early-warning systems for water quality management in untreated source waters, especially in geographically isolated areas where conventional monitoring is logistically challenging. By detecting genetic markers that signal the onset of toxin production, water managers can implement proactive measures to mitigate health risks before toxins reach dangerous levels.
Moreover, the integration of molecular diagnostics with traditional chemical assays bridges a vital gap between potential toxicity indicated by gene presence and actual toxin concentrations. This holistic understanding supports more informed decision-making, enhancing public safety and resource management.

In conclusion, this multi-tiered monitoring framework represents a significant advancement in environmental water quality surveillance. It demonstrates the critical importance of combining molecular biology tools with chemical analytics to effectively monitor, predict, and manage cyanobacterial toxin risks. Adoption of such integrated methodologies can transform water quality monitoring programs, providing early detection and actionable intelligence necessary for safeguarding drinking water sources and ecological health.