Cultivating electroactive microbes—from field to bench

Mon Oo Yee,Amelia-Elena Rotaru,Alfred Spormann,Joerg Deutzmann

doi:10.1088/1361-6528/ab6ab5

Mon Oo Yee, Amelia-Elena Rotaru + Show 2 more

Open Access

https://doi.org/10.1088/1361-6528/ab6ab5

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Abstract

Electromicrobiology is an emerging field investigating and exploiting the interaction of microorganisms with insoluble electron donors or acceptors. Some of the most recently categorized electroactive microorganisms became of interest to sustainable bioengineering practices. However, laboratories worldwide typically maintain electroactive microorganisms on soluble substrates, which often leads to a decrease or loss of the ability to effectively exchange electrons with solid electrode surfaces. In order to develop future sustainable technologies, we cannot rely solely on existing lab-isolates. Therefore, we must develop isolation strategies for environmental strains with electroactive properties superior to strains in culture collections. In this article, we provide an overview of the studies that isolated or enriched electroactive microorganisms from the environment using an anode as the sole electron acceptor (electricity-generating microorganisms) or a cathode as the sole electron donor (electricity-consuming microorganisms). Next, we recommend a selective strategy for the isolation of electroactive microorganisms. Furthermore, we provide a practical guide for setting up electrochemical reactors and highlight crucial electrochemical techniques to determine electroactivity and the mode of electron transfer in novel organisms.

Highlights

IntroductionLiving things conserve energy by translocating electrons from an organic food substrate (electron donor) to a terminal electron acceptor (e.g. oxygen) via redox reactions in a respiratory chain
Living things conserve energy by translocating electrons from an organic food substrate to a terminal electron acceptor via redox reactions in a respiratory chain
We provide an overview of the studies that isolated or enriched electroactive microorganisms from the environment using an anode as the sole electron acceptor or a cathode as the sole electron donor

Summary

Introduction

Living things conserve energy by translocating electrons from an organic food substrate (electron donor) to a terminal electron acceptor (e.g. oxygen) via redox reactions in a respiratory chain. The ability to exchange electrons with the extracellular milieu provides a selective advantage for electroactive microbes in a variety of ecological niches in the environment Of these pre-adapted electroactive species we can selectively isolate novel strains, characterize them, and use their properties in sustainable technologies relying on bioelectrochemical systems. Many authors applied one ineffective strategy for the isolation of electroactive microorganisms, which is aerobic cultivation with nutrient-rich agar (table 1) [111, 122,123,124, 131, 136,137,138,139,140,141,142] This strategy favors fastgrowing, oxygen-respiring organisms over electrotrophic ones, obscuring downstream electrochemical studies, and interpretation of data.

12. Insert butyl stoppers and crimp seal all side ports of the H-cells

22. Initiate electrochemical measurements

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