Engineering Wired Life: Synthetic Biology for Electroactive Bacteria

Abstract

Electroactive bacteria produce or consume electrical current by moving electrons to and from extracellular acceptors and donors. This specialized process, known as extracellular electron transfer, relies on pathways composed of redox active proteins and biomolecules and has enabled technologies ranging from harvesting energy on the sea floor, to chemical sensing, to carbon capture. Harnessing and controlling extracellular electron transfer pathways using bioengineering and synthetic biology promises to heighten the limits of established technologies and open doors to new possibilities. In this review, we provide an overview of recent advancements in genetic tools for manipulating native electroactive bacteria to control extracellular electron transfer. After reviewing electron transfer pathways in natively electroactive organisms, we examine lessons learned from the introduction of extracellular electron transfer pathways into Escherichia coli. We conclude by presenting challenges to future efforts and give examples of opportunities to bioengineer microbes for electrochemical applications.

Ultrasonic pre-treatment of Bacillus velezensis for improved electrogenic response in a single chambered microbial fuel cell

“…Various studies on electrochemical evaluation of different microorganisms from various environments and their 16 s rRNA gene sequence analysis indicate that more phylogenetic and physiologically diverse microorganisms may be successfully used as in the MFC assembly (Naradasu et al 2019). A number of pure cultures have already been identified that can conduct EET with suitable electrodes from a variety of habitats (Zuo et al 2008;Bird et al 2021). One such source is the cow's intestine, which has a reductive and an anaerobic setting, where fermentation is the predominant mode of microbial metabolism in which nicotinamide adenine dinucleotide (NADH) induces the reduction and oxidation of organic substrates (De Menezes et al 2011;Fritts et al 2021).…”

Strategies for Improving Small-Molecule Biosensors in Bacteria

“…In bacteria, antibiotic resistance genes are commonly selected for this purpose [ 143 ]; however, the use of auxotrophic markers has also been described [ 144 ]. Outside of established systems, recent studies have continued to develop new types of reporters, including genes producing electrical signal [ 145 ], gas production [ 146 ], and targeted genome editing [ 147 , 148 ].…”

“…When using less common reporter genes, however, more complex or specialized equipment can be required. For example, reporters producing electroactive signal can require a bioelectronic sensing system [ 145 ]. In previous work using reporters that function through gas production, a gas chromatograph-mass spectrometer (GC-MS) was required [ 146 ].…”

Electrogenic Bacteria Promise New Opportunities for Powering, Sensing, and Synthesizing

“…[ 16–19 ] Many studies have explored ways to improve the MFC performance through nanotechnologies, genetic engineering of bacteria, and material innovations. [ 13,20,21 ] However, their integration into the large‐scale footprint cost‐effectively and robustly is questionable. Although stacking of modular small MFC units has been proposed as an alternative solution for large‐scale development, the performance has not noticeably improved because of intrinsic voltage reversal and mass transport limitations within the serially connected units.…”

“…[16][17][18][19] Many studies have explored ways to improve the MFC performance through nanotechnologies, genetic engineering of bacteria, and material innovations. [13,20,21] However, their integration into the large-scale footprint cost-effectively and robustly is questionable. Although stacking of modular Considerable research efforts into the promises of electrogenic bacteria and the commercial opportunities they present are attempting to identify potential feasible applications.…”