Investigating Variability in Microbial Fuel Cells.

Area of Science:

• Microbial Ecology
• Bioelectrochemistry

Background:

• Reproducibility is crucial in scientific studies, yet challenging in microbial experiments using diverse, real-world inocula.
• Stochastic processes in subsampling natural microbial diversity lead to heterogeneous communities in reactors and biofilms.
• Microbial fuel cells (MFCs) provide a quantifiable system to study community development and variability through real-time current measurement.

Purpose of the Study:

• To investigate the reproducibility of microbial communities in replica microbial fuel cells (MFCs) under identical conditions.
• To quantify the variability in current production and community development within these replica MFCs.
• To explore methods for controlling variability, including reseeding with established communities.

Main Methods:

• Construction and operation of 28 replica MFCs under identical conditions.
• Real-time monitoring of current production to assess community metabolism and development.
• Subsequent feeding rounds and reseeding experiments to evaluate variability control.

Main Results:

• Significant variability was observed in the rate and amount of current production among replica MFCs.
• This heterogeneity persisted across multiple feeding rounds, even with new inocula.
• Reseeding with established "good" and "bad" reactors did not produce replica biofilms, indicating spatial and compositional influences.

Conclusions:

• Identical conditions and mixed inocula result in emergent microbial communities with differing metabolic capabilities.
• High variability in replica reactors is a fundamental microbial process that requires further investigation.
• Current research practices often underestimate this variability by using limited replicates (duplicates or triplicates).