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UBC Theses and Dissertations

Development of a high throughput biofilm formation assay for microbial fuel cell performance screening Mason, Marie

Abstract

Microbial Fuel Cells (MFC) are an emerging research field due to their ability to simultaneously tackle two prominent environmental concerns. MFCs are a clean waste valorization biotechnology that utilize microorganisms as biocatalysts to metabolize substrates available in wastewater, yielding renewable energy and clean water as a by-product. Despite their potential, MFCs face significant hurdles that hinder their practical application in industry. Consequently, research efforts are largely directed towards enhancing MFC performance by refining various components and operational parameters. This research is often labour intensive, time consuming and costly. This thesis aims to expedite MFC research through the development of a high-throughput biofilm formation assay tailored for MFC performance screening. The developed high-throughput plate reader assay enables real-time quantification of biofilm attachment to electrodes, to determine the cell load ratio. This assay is a novel achievement in biofilm quantification, as no other known method can numerically quantify living biofilm on an electrode surface. It serves as a versatile tool for comparing various MFC components such as electrode materials or treatments, bacterial strains, media and operating conditions like temperature, agitation rates or additives. The developed assay offers simplicity, cost-effectiveness, and scalability, thereby streamlining the evaluation process. To validate its efficacy, the assay was utilized to compare three distinct electrode conditions: untreated, ethanol-treated, and autoclaved electrodes. Results obtained from the plate-reader assay were corroborated using traditional electrochemical methods, including chronoamperometry to find current outputs and electrochemical impedance spectroscopy to determine overall MFC impedance. It was observed that a slower biofilm development rate proved more beneficial than achieving a higher biofilm attachment loading ratio, relative to the planktonic cell culture. A correlation was established indicating that the longer it took to achieve the maximum load ratio, the less impedance and greater current outputs exhibited by the MFC. This implies that a gradual cell attachment process enhances the electroactivity of the biofilm, thereby enhancing MFC performance. This trend was consistent across all three electrode test conditions. Notably, ethanol-treated electrodes exhibited the most promising performance, characterized by the longest peak load ratio time, lowest impedance, and highest current outputs, followed by autoclaved and untreated electrodes, respectively.

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Attribution-NonCommercial-NoDerivatives 4.0 International