A genetically encoded fluorescent whole-cell biosensor for real-time detecting estrogenic activities in water samples

Area of Science:

• Environmental Science
• Biotechnology
• Analytical Chemistry

Background:

• Real-time monitoring of estrogenic activity in aquatic environments is crucial but challenging.
• Existing biosensors struggle with response speed and tolerance in complex matrices like wastewater.
• Wastewater is a primary source of estrogenic compounds, posing risks to aquatic ecosystems.

Purpose of the Study:

• To develop a novel whole-cell bacterial biosensor for rapid and reliable detection of net estrogenic activity.
• To engineer a biosensor with enhanced environmental tolerance for real-world wastewater monitoring.
• To establish a practical tool for assessing estrogenic pollution in aquatic environments.

Main Methods:

• Engineered Escherichia coli by integrating the estrogen receptor (ER) sensing domain into a fluorescent protein (FP) Citrine, creating the ER-Light biosensor.
• Expressed the engineered FP in the bacterial periplasm for estrogen detection.
• Validated ER-Light's performance in terms of response time, sensitivity, working range, and tolerance to wastewater effluent.

Main Results:

• ER-Light demonstrated a rapid response time of 40 seconds for detecting estrogenic activity.
• Achieved a low detection limit (4.55 × 10⁻⁷ μM) and a suitable working range (up to 1.1 × 10⁻⁴ μM).
• Showcased high recovery rates (91.0–102.1%) in wastewater effluent, indicating minimal matrix effects and practical applicability.

Conclusions:

• ER-Light is the first FP-based biosensor integrating ER for environmental monitoring, offering real-time detection of estrogenic activity.
• The biosensor is robust, sensitive, and tolerant to wastewater, providing accurate measurements of estradiol equivalent concentration (EEQ).
• Findings offer design principles for bioactivity monitoring, contributing to ecological and human health protection.