Weak electricigens : a new avenue for bioelectrochemical research

Electroactivity appears to be a phylogenetically diverse trait independent of cell wall classification, with both Gram-negative and Gram-positive electricigens reported. While numerous electricigens have been observed, the majority of research focuses on a select group of highly electroactive species. Under favorable conditions, many microorganisms can be considered electroactive, either through their own mechanisms or exogenously-added mediators, producing a weak current. Such microbes should not be dismissed based on their modest electroactivity. Rather, they may be key to understanding what drives extracellular electron transfer in response to transient limitations of electron acceptors or donor, with implications for the study of certain pathogens. Due to their low electroactivity, such populations are difficult to grow in bioelectrochemical systems and characterise with electrochemistry. Here, we provide a critical review of recent research on weak electricigens, their relevance to microbial ecology and bioelectrochemical systems, and an assessment of the methods commonly used to observe them.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)Accepted versio