Microbial current production from Streptococcus mutans correlates with biofilm metabolic activity
Divya Naradasu1, Alexis Guionet2, Waheed Miran2
1International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan; Department of Advanced Interdisciplinary Studies, RCAST, Graduate School of Engineering, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan.
Biosensors & Bioelectronics
|May 12, 2020
Summary
We discovered that the oral pathogen Streptococcus mutans produces electrical current from its biofilm, reflecting its metabolic activity. This finding enables new electrochemical methods to study biofilm behavior and develop antibiofilm strategies.
Area of Science:
- Microbiology
- Electrochemistry
- Biofilm research
Background:
- Biofilms formed by pathogens exhibit increased tolerance to drugs and resistance to removal.
- Biofilm robustness is linked to the metabolic activity of constituent microbes.
- Direct assays for quantifying biofilm metabolic activity are crucial for developing antibiofilm strategies.
Purpose of the Study:
- To investigate current production by the oral pathogen Streptococcus mutans biofilm.
- To establish a direct electrochemical assay for assessing biofilm metabolic activity in situ.
- To explore the correlation between extracellular electron transport (EET) and metabolic activity in S. mutans biofilms.
Main Methods:
- Utilized single-potential amperometry (SA) to measure current production from S. mutans biofilms on an electrode.
- Assessed the effect of the metabolic inhibitor Triclosan on current production.
- Employed high-resolution mass spectroscopy to quantify nitrogen-15 (¹⁵N) fixation as a measure of anabolic activity.
- Proposed the combination of SA and electrochemical impedance spectroscopy (EIS) for comprehensive biofilm analysis.
Main Results:
- S. mutans biofilms produced anodic current on a +0.4 V electrode in the presence of glucose within 8 hours.
- Current production was significantly reduced by Triclosan, indicating metabolic dependence.
- Higher current production correlated with increased ¹⁵N fixation, confirming reflection of metabolic activity.
- EIS can quantify bacterial adhesion, complementing SA for time-dependent metabolic and physiological assessments.
Conclusions:
- Electrical current production by S. mutans biofilms directly reflects their metabolic activity.
- The combination of SA and EIS offers a novel, non-invasive assay for quantifying biofilm metabolic activity and response to compounds.
- This electrochemical approach provides a new tool for studying EET-capable pathogens and developing antibiofilm interventions.
