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• 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]

[Display omitted] • Shewanella loihica PV-4 exhibited high performance in reducing CO 2 to formate. • A novel three-dimensional biological self-assembled cathode was constructed. • No involvement of electron mediators was found in whole cell catalysis. • Faraday efficiency of bioelectrosynthetic CO 2 -to-formate reached 99.95%. Bioelectrochemical CO 2 reduction (bio-CO 2 R) provides a sustainable and carbon neutral power-to-chemical route. Whole-cell electrosynthesis is one of the attractive strategies to realize CO 2 R due to its simple and low-cost superiorities. However, it is still challenging to overcome the sluggish transmembrane electron transfer of microorganisms without exogenously added mediators. Here, we described the fabrication of biohydrogel that contains bio-reduced graphene oxide (rGO) and living electroactive bacteria (EAB) for bio-CO 2 R. The EAB exhibited surprising ability to self-assemble biohydrogel that was further served as biocathode to drive CO 2 -to-formate electrosynthesis. With the close interaction between EAB and rGO nanosheets, the transmembrane electron transfer achieved at high Faradaic efficiency (∼99.5 %) and 46-fold increase of formate titer without exogenous mediator. This work provided the facile and practical approach to bridge the bacterial cell and electrode for efficient electron transfer and implied the new possibility to store the electric energy into chemicals with bio-CO 2 R. [ABSTRACT FROM AUTHOR]

• Graphene was in-situ formed in AD-MEC system. • Voltage stimulation, graphene, and increased biomass promote AD efficiency. • Biogas yield in the VGG system was 356.49 m3/t dry swine manure. • Methanosarcina and Methanobrevibacter predominated in VGG system. • Microorganisms were more trended to gather in VGG system with the network analysis. The aim of this work was to enhance methane production from swine manure anaerobic digestion (AD) with in-situ formed graphene in microbial electrolysis cell (AD-MEC). The AD-MEC for in-situ graphene exfoliation incorporated a carbon felt anode and a titanium mesh cathode with an applied voltage of 2.5 V. Atomic force microscopic and Raman analyses confirmed that the graphene was in-situ formed. Voltage stimulation (1 h per day) and graphene production enhanced AD efficiency by promoting direct interspecies electron transfer between AD microorganisms. The increased biomass owing to enrichment of AD microorganisms on the carbon felt could also enhance AD efficiency. The voltage-graphene group (VGG) greatly enhanced the biogas yield (356.49 m3/t dry swine manure) and methane yield (222.17 m3/t dry swine manure), which were 41.49% and 60.89% higher than that of the control group, respectively. Microbial community analysis identified the dominant methanogens in the VGG system as Methanosarcina and Methanobrevibacter , while only Methanosarcina was dominant in the control system. Network analysis showed that the VGG system established a narrower niche than the control system, and microorganisms trended to gather more in the module. [ABSTRACT FROM AUTHOR]

• Cytocompatible bacterial ATRP (b- ATRP) was developed. • Bacterial nanohybrids with high viability were obtained with b -ATRP. • The surface electric property of bacterial cells was well-controlled by b- ATRP. • Cr(VI) removal rate was improved by 3 times with bacterial nanohybrid. Surface-initiated activator regenerated by electron transfer atom transfer radical polymerization (SI-ARGET ATRP) has great potential to modify living cell surface with controlled architecture and tailored phenotype. However, it is challenging to engineer the bacterial cells with current SI-ARGET ATRP due to low cellular tolerance to the toxic reagents in polymerization. In this study, a cytocompatible bacterial SI-ARGET ATRP (b -ATRP) strategy was developed for individual nanoencapsulation of living bacterial cell. With step by step optimization of reaction conditions, living nanohybrid with high cell viability (>70%) was achieved with b -ATRP. Furthermore, living Shewanella nanohybrids with controllable surface electric property were fabricated with b -ATRP and applied for aqueous Cr(VI) treatment. Impressively, nanoencapsulation of cells with poly(4-vinylpyridine) improved the Cr(VI) removal rate by 3 times. This work provided a new approach to engineer the living bacterial cell surface and expanded the ATRP applications to prokaryotic cell and bioremediation. [ABSTRACT FROM AUTHOR]