eDNA- and eRNA-Based Detection of 2-Methylisoborneol-Producing Cyanobacteria and Intracellular Synthesis Dynamics in...

Area of Science:

• Environmental microbiology
• Water quality monitoring
• Cyanobacterial toxin prediction

Background:

• Taste and odor (T&O) compounds in freshwater are often produced by cyanobacteria, but predicting their occurrence is challenging.
• The 2-methylisoborneol (2-MIB) compound is a common T&O substance synthesized via the mibC gene in certain cyanobacteria.

Purpose of the Study:

• To investigate the temporal and spatial dynamics of the mibC gene using environmental DNA (eDNA) and environmental RNA (eRNA).
• To assess the predictive capability of eRNA for 2-MIB concentration and T&O events in freshwater systems.

Main Methods:

• Analysis of mibC gene presence (DNA) and expression (RNA) via quantitative PCR (qPCR).
• Measurement of cyanobacterial cell density (microscopy) and 2-MIB concentration (gas chromatography-mass spectrometry).
• Sampling conducted across twelve sites in the North Han River over 27 months.

Main Results:

• The mibC gene was detected year-round, with peak DNA concentrations from late summer to early winter, often originating upstream.
• eRNA expression correlated strongly with 2-MIB concentrations (r = 0.879), preceding increases by 2-4 weeks.
• eRNA levels showed a moderate association with Pseudanabaena cell density, while eDNA correlations were weaker.

Conclusions:

• Environmental RNA (eRNA) monitoring serves as a valuable early warning tool for impending taste and odor events.
• Integrating eDNA and eRNA analyses enhances the evaluation of T&O-producing cyanobacteria, aiding proactive drinking water management.