Biochar is a by-product of thermochemical conversion of biomass or other carbonaceous materials. Recently, it has garnered extensive attention for its high application potential in microbial fuel cell (MFC) systems owing to its high conductivity and low cost. However, the effects of biochar on MFC system performance have not been comprehensively reviewed, thereby necessitating the evaluation of the efficacy of biochar application in MFCs. In this review, biochar characteristics were outlined based on recent publications. Subsequently, various applications of biochar in the MFC systems and their probable processes were summarized. Finally, proposals for future applications of biochar in MFCs were explored along with its perspectives and an environmental evaluation in the context of a circular economy. The purpose of this review is to gain comprehensive insights into the application of biochar in the MFC systems, offering important viewpoints on the effective and steady utilization of biochar in MFCs for practical application.

A novel bacterial strain, designated NS28^T, was isolated from interfacial sediment sampled at Taihu Lake, PR China. Cells were rod-shaped, Gram-negative, aerobic and non-motile on Reasoner's 2A medium. The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NS28^T was most closely related to species from the genus Dyadobacter , with 98.4 and 96.0 % 16S rRNA gene sequence similarity to its closest phylogenetic neighbours Dyadobacter sediminis CGMCC 1.12895^T and Dyadobacter luticola CCTCC AB 2017091^T, respectively. MK-7 was the only cellular menaquinone. The major fatty acids were summed feature 3 (C_16 : 1ω7c and/or C_16 : 1ω6c), iso-C_15 : 0 and C_16 : 1ω5c. The major polar lipids were phosphatidylethanolamine, one phospholipid, one aminolipid, one lipid and two unidentified lipids. Genomic analysis of strain NS28^T indicated that the total genome size was 6 477 094 bp with a G+C content of 44.8 mol%, 5380 protein-coding genes, 79 contigs and an N50 length of 299584 bp. On the basis of the genomic DNA sequence, the average nucleotide identity values were 90.5 and 74.1 % with D. sediminis CGMCC 1.12895^T and D. luticola CCTCC AB 2017091^T, respectively. Digital DNA-DNA hybridization results of strain NS28^T with D. sediminis CGMCC 1.12895^T and D. luticola CCTCC AB 2017091^T were 40.9 and 18.6 %, respectively. Based on the phenotypic, chemotaxonomic, phylogenetic and genome sequence data presented here, it is proposed that strain NS28^T represents a novel species of the genus Dyadobacter for which the name Dyadobacter flavalbus is proposed . The type strain is NS28^T (=NBRC 113854^T=MCCC 1K03764^T).

An aerobic, Gram-stain-negative, non-spore-forming and rod-shaped bacterial strain, designated N8^T, was isolated from the interfacial sediment of Taihu Lake in PR China. The strain formed white to blue colonies on R2A agar. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain N8^T represented a member of the genus Gemmobacter and was most closely related to Gemmobacter aquaticus A1-9^T (97.97 %). The average nucleotide identity and digital DNA–DNAhybridization values between strain N8^T and G. aquaticus A1-9^T based on their whole genomes were 78.8 and 21.7 %, respectively. Q-10 was the main predominant ubiquinone. The major fatty acids were summed feature 8 (C_18 : 1ω7c and/or C_18 : 1ω6c), C_18 : 0 and C_16 : 0. The G+C content of the genomic DNA was 66.1 mol%. The polar lipids comprised phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, one unidentified phospholipid, two unidentified glycolipids and two unidentified lipids. Based on its physiological, biochemical and chemotaxonomic characteristics, strain N8^T represents a novel species of the genus Gemmobacter , for which the name Gemmobacter caeruleus sp. nov. is proposed. The type strain is N8^T=(KACC 21307^T=MCCC 1K04036^T).

A novel Gram-stain-negative, aerobic and rod-shaped bacterial strain, designated H-1T, was isolated from the interfacial sediment of Taihu Lake in China and characterized by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the organism was most closely related to Rufibacter immobilis MCC P1T and Rufibacter tibetensis 1351T, with sequence similarities of 98.0 and 97.6 %, respectively. DNA–DNA relatedness between strain H-1T and R. immobilis MCC P1T and R. tibetensis 1351T was 48.8 and 36.6 %, respectively. The major (>5 %) cellular fatty acids were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 1ω5c, iso-C15 : 0, summed feature 4 (iso-C17 : 1 I and/or anteiso-C17 : 1 B) and anteiso-C15 : 0. The polar lipids comprised phosphatidylethanolamine, three unidentified aminophospholipids, an unidentified phospholipid and three unidentified lipids. The major respiratory quinone was menaquinone 7 (MK-7). Genomic DNA G+C content was 49.0 mol%. Based on its physiological, biochemical and chemotaxonomic characteristics, the strain represents a novel species of the genus Rufibacter , for which the name Rufibacter sediminis sp. nov. (type strain H-1T=CGMCC 1.16289T=NBRC 113030T) is proposed.