On-line monitoring of heavy metals-related toxicity with a microbial fuel cell biosensor

Abstract

This study describes an environmental biosensor for real time toxicity monitoring, which exploits high sensitivity of a microbial fuel cell (MFC) to variations in concentrations of electron donors and acceptors. Fast biosensor response to changes in total heavy metal concentration of a mining rock drainage was observed in laboratory tests with acceptable repeatability and a coefficient of determination (R²) of 0.95-0.97. The biosensor response is attributed to interference of heavy metals with the activity of electroactive microorganisms. Biomolecular analysis of the anodic electroactive biofilms showed significant population differences between microbial populations of the biosensor exposed to heavy metals and a non-exposed (control) biosensor. Furthermore, the biosensor outputs were highly correlated (R² = 0.92) with the results of the Microtox toxicity assay. The results of this study contribute towards the development of a simple MFC-based biosensor capable of detecting, in real-time, changes in environmental conditions and providing a tool for on-site toxicity monitoring.

Keywords: Biosensor; MFC; Mining effluent; Real-time; Toxicity.