A laminar-flow microfluidic device for quantitative analysis of microbial electrochemical activity

Area of Science:

• Microbiology
• Electrochemistry
• Bioengineering

Background:

• Microbial electrochemical systems (MES) are crucial for understanding microbial respiration and energy conversion.
• Developing rapid and controlled environments for studying microbial electrochemical activity is essential.

Purpose of the Study:

• To develop and characterize a laminar flow-based microfluidic bioelectrochemical system (BES).
• To investigate the rapid response of Geobacter sulfurreducens to chemical stimuli within a microfluidic environment.
• To assess the potential of anthraquinone disulfide (AQDS) as a redox mediator.

Main Methods:

• Fabrication of a microfluidic BES using polydimethyl siloxane (PDMS) channels and gold electrodes.
• Culturing Geobacter sulfurreducens strain PCA under strict anaerobic conditions within the microfluidic system.
• Potentiostatically controlled two-electrode operation with rapid exposure to stimuli (O2, AQDS) and analysis of current production.

Main Results:

• The microfluidic BES demonstrated short hydraulic retention times (≈ 2 min) and response times (<21 min).
• Short-term exposure to oxygen did not cause irreversible toxicity to Geobacter sulfurreducens.
• Anthraquinone disulfide (AQDS) was confirmed as an effective redox mediator for electron shuttling.

Conclusions:

• The developed microfluidic BES is a promising tool for rapid electrochemical studies of microbial activity.
• Laminar flow in microfluidics allows for a well-defined electrochemical environment without membrane separation.
• This system facilitates real-time investigation of microbial electrochemical processes and responses to environmental changes.