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Direct interspecies electron transfer (DIET) is essential for maintaining the function and stability of anaerobic microbial consortia. However, only limited natural DIET modes have been identified and DIET engineering remains highly challenging. In this study, an unnatural DIET between Shewanella oneidensis MR‐1 (SO, electron donating partner) and Rhodopseudomonas palustris (RP, electron accepting partner) was artificially established by a facile living cell‐cell click chemistry strategy. By introducing alkyne‐ or azide‐modified monosaccharides onto the cell outer surface of the target species, precise covalent connections between different species in high proximity were realized through a fast click chemistry reaction. Remarkably, upon covalent connection, outer cell surface C‐type cytochromes mediated DIET between SO and RP was achieved and identified, although this was never realized naturally. Moreover, this connection directly shifted the natural H2 mediated interspecies electron transfer (MIET) to DIET between SO and RP, which delivered superior interspecies electron exchange efficiency. Therefore, this work demonstrated a naturally unachievable DIET and an unprecedented MIET shift to DIET accomplished by cell‐cell distance engineering, offering an efficient and versatile solution for DIET engineering, which extends our understanding of DIET and opens up new avenues for DIET exploration and applications. [ABSTRACT FROM AUTHOR]

• The combination of natural microbe species enhanced both direct and indirect electron transport mechanisms. • The alliance system expands the utilization spectra of the carbon source. • Riboflavin and Phenazine two electron shuttles work in coordination. Microbial fuel cells with mixed bacteria always show better power output capacity than those with single bacteria due to synergetic effects between species. Here, a rational-designed synthetic three-species alliance system based on Shewanella oneidensis MR-1 (the model exoelectrogen), Pseudomonas aeruginosa, and Lactobacillus plantarum was constructed upon process optimization, the three-species alliance system in MFC delivered a maximum power density of ∼ 207 mW/m2 by using the glucose as the substrate, which was 2 ∼ 58 times higher than that of MFC inoculated with single species. In addition, the synthetic alliance system could generate electricity from broad substrate spectrum (lactose, saccharose, maltose, arabinose, cellobiose) with enhanced performance. Electrochemical and metabolism analysis indicated inter-species synergetic enhancement on charge transfer, substrate utilization, and biofilm formation was the underlying mechanism for performance improvement in MFC by this synthetic alliance system. In this system, L. plantarum uses glucose to produce lactic acid as the electrogenic substrate and electron donor of S. oneidensis MR-1, and P. aeruginosa uses glucose to produce another electron shuttle phenazine, which can also promote the growth of S. oneidensis MR-1 biofilm and help the alliance system to transfer electrons better. This work demonstrated a new strategy to enhance the MFC performance with a rational designed synthetic bacterial community, which would further renew the toolbox for MFC optimization. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) macroporous reduced graphene oxide/polypyrrole (rGO/Ppy) hydrogel assembled by bacterial cells was fabricated and applied for microbial fuel cells. By taking the advantage of electroactive cell-induced bioreduction of graphene oxide and in-situ polymerization of Ppy, a facile self-assembly by Shewanella oneidensis MR-1and in-situ polymerization approach for 3D rGO/Ppy hydrogel preparation was developed. This facile one-step self-assembly process enabled the embedding of living electroactive cells inside the hydrogel electrode, which showed an interconnected 3D macroporous structures with high conductivity and biocompatibility. Electrochemical analysis indicated that the self-assembly of cell-embedding rGO/Ppy hydrogel enhanced the electrochemical activity of the bioelectrode and reduced the electron charge transfer resistance between the cells and the electrode. Impressively, extremely high power output of 3366 ± 42 mW m−2 was achieved from the MFC with cell-embedding rGO/Ppy hydrogel rGO/Ppy, which was 8.6 times of that delivered from the MFC with bare electrode. Further analysis indicated that the increased cell loading by the hydrogel and improved electrochemical activity by the rGO/Ppy composite would be the underlying mechanism for this performance improvement. This study provided a facile approach to fabricate the biocompatible and electrochemical active 3D nanocomposites for MFC, which would also be promising for performance optimization of various bioelectrochemical systems. [Display omitted] • Cell-embedding rGO/Ppy hydrogel was assembled by bacterial cells. • The biohydrogel showed high cell viability and excellent electrochemical activity. • Efficient extracellular electron transfer between cell and electrode was achieved. • Extremely high power output of 3366 ± 42 mW m−2 was achieved from the MFC. [ABSTRACT FROM AUTHOR]

Whole-cell biosensors are an important class of analytical tools that offer the advantages of low cost, facile operation, and unique reproduction/regeneration ability. However, it has always been quite challenging to expand the sensing spectrum of the host. Here, a new approach to extend the cell sensing spectrum with biomineralized nanoparticles is developed. The nano-biohybrid design comprise biomineralized FeS nanoparticles firmly anchored onto the bacterium, Shewanella oneidensis MR-1, wherein the nanoparticles are wired to the cellular electron transfer machinery (MtrCAB/OmcA) of the bacterium, forming an artificial cyborgian redox machinery consisting of FeS-MtrCAB/OmcA-FccA. Strikingly, with this cyborgian redox machinery, the sensing spectrum of FeS hybridized S. oneidensis MR-1 cell is successfully expanded to enable whole-cell electrochemical detection of Vitamin B12, while an unhybridized native cell is incapable of sensing. This proof-of-concept nano-biohybrid design offers a new perspective on manipulating the microbial toolkit for an expanded sensing spectrum in whole-cell biosensors. [Display omitted] • A nano-hybridized electroactive bacteria based system was assembled. • Artificial cyborgian redox machinery was identified in this biohybrid cell. • This cyborgian redox machinery expanded the sensing spectrum of Shewanella cell. • A sensitive whole-cell biosensing system for VB12 was developed. [ABSTRACT FROM AUTHOR]

Although microbial fuel cells (MFCs) is considered as one of the most promising technology for renewable energy harvesting, low power output still accounts one of the bottlenecks and limits its further development. In this work, it is found that Cu 2+ (0.1 μg L −1 –0.1 mg L −1 ) or Cd 2+ (0.1 μg L −1 –1 mg L −1 ) significantly improve the electricity generation in MFCs. The maximum power output achieved with trace level of Cu 2+ (∼6 nM) or Cd 2+ (∼5 nM) is 1.3 times and 1.6 times higher than that of the control, respectively. Further analysis verifies that addition of Cu 2+ or Cd 2+ effectively improves riboflavin production and bacteria attachment on the electrode, which enhances bacterial extracellular electron transfer (EET) in MFCs. These results unveil the mechanism for power output enhancement by Cu 2+ or Cd 2+ addition, and suggest that metal ion addition should be a promising strategy to enhance EET as well as power generation of MFCs. [ABSTRACT FROM AUTHOR]