Activity Of Bacteria Research Articles

Novel antimicrobial iodo-dihydro-pyrrole-2-one compounds.

Aim: A series of new hybrid molecules with two iodine atoms on thesides were synthesized. Methods: A one-pot, two-component methodwith trifluoroacetic acid as aneffective catalystto obtain dihydro-pyrrol-2-one compoundswas developed. Short reaction times, acheap catalyst, high yields and clean work-up are benefits of this method. Results: The chemical structures of thenewly synthesized compounds were verified through spectroscopic techniques. Their antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans was tested in vitro. Conclusion: NC- and OH- radicals confer broad-spectrum antimicrobial activity, including againstGram-positive and Gram-negative bacteria and yeasts. Compounds 3g >7 and>9 were most active on the two bacterial species, while 3l >9 and >3i were most active against the fungal strain.

Flagella of Tumor-Targeting Bacteria Trigger Local Hemorrhage to Reprogram Tumor-Associated Macrophages for Improved Antitumor Therapy.

Tumor-associated macrophages (TAMs) exhibit an immunosuppressive M2 phenotype and lead to failure of antitumor therapy. Infiltrated erythrocytes during hemorrhage are recognized as a promising strategy for polarizing TAMs. However, novel materials that precisely induce tumor hemorrhage without affecting normal coagulation still face challenges. Here, tumor-targeting bacteria (flhDC VNP) are genetically constructed to realize precise tumor hemorrhage. FlhDC VNP colonizes the tumor and overexpresses flagella during proliferation. The flagella promote the expression of tumor necrosis factor α, which induces local tumor hemorrhage. Infiltrated erythrocytes during the hemorrhage temporarily polarize macrophages to the M1 subtype. In the presence of artesunate, this short-lived polarization is transformed into a sustained polarization because artesunate and heme form a complex that continuously produces reactive oxygen species. Therefore, the flagella of active tumor-targeting bacteria may open up new strategies for reprogramming TAMs and improving antitumor therapy.

Fat, oil, and grease as new feedstock towards bioelectrogenesis in microbial fuel cells: Microbial diversity, metabolic pathways, and key enzymes

Microbial fuel cells (MFCs) are a well-known technology used for bioelectricity production from the decomposition of organic waste via electroactive microbes. Fat, oil, and grease (FOG) as a new substrate in the anode and microalgae in the cathode were added to accelerate the electrogenesis. The effect of FOG concentrations (0.1%, 0.5%, 1%, and 1.5%) on the anode chamber was investigated. The FOG degradation, volatile fatty acid (VFAs) production, and soluble chemical oxygen demand along with voltage output kinetics were analyzed. Moreover, the microbial community analysis and active functional enzymes were also evaluated. The maximum power and current density were observed at 0.5% FOG which accounts for 96 mW m−2 (8-folds enhancement) and 560 mA m−2 (3.7-folds enhancement), respectively. The daily voltage output enhanced upto 2.3-folds with 77.08% coulombic efficiency under 0.5% FOG, which was the highest among all the reactors. The 0.5% FOG was degraded >85%, followed by a 1% FOG-loaded reactor. The chief enzymes in β-oxidation and electrogenesis were acetyl-CoA C-acetyltransferase, riboflavin synthase, and riboflavin kinase. The identified enzymes symbolize the presence of Clostridium sp. (>15%) and Pseudomonas (>10%) which served as electrochemical active bacteria (EAB). The major metabolic pathways involved in electrogenesis and FOG degradation were fatty acid biosynthesis and glycerophospholipid metabolism. Utilization of lipidic-waste (such as FOG) in MFCs could be a potential approach for simultaneous biowaste utilization and bioenergy generation.

Immunometabolic control by Klebsiella pneumoniae.

Klebsiella pneumoniae is a common Gram-negative pathogen associated with community-acquired and healthcare-associated infections. Its ability to acquire genetic elements resulted in its rapid development of resistance to virtually all antimicrobial agents. Once infection is established, K. pneumoniae is able to evade the host immune response and perhaps more importantly, undergo metabolic rewiring to optimize its ability to maintain infection. K. pneumoniae lipopolysaccharide and capsular polysaccharide are central factors in the induction and evasion of immune clearance. Less well understood is the importance of immunometabolism, the intersection between cellular metabolism and immune function, in the host response to K. pneumoniae infection. Bacterial metabolism itself is perceived as a metabolic stress to the host, altering the microenvironment at the site of infection. In this review, we will discuss the metabolic responses induced by K. pneumoniae, particularly in response to stimulation with the metabolically active bacteria versus pathogen-associated molecular patterns alone, and their implications in shaping the nature of the immune response and the infection outcome. A better understanding of the immunometabolic response to K. pneumoniae may help identify new targets for therapeutic intervention in the treatment of multidrug-resistant bacterial infections.

Synergistic effect of zero-valent iron and static magnetic field on wastewater purification and bioelectricity generation in electroactive constructed wetlands

This study investigated the enhancement effect of zero-valent iron and static magnetic field on the pollutant removal and power generation of electroactive constructed wetland. As demonstration, a conventional wetland was systematically modified by introducing zero-valent iron and then a static magnetic field, leading to progressive increases in pollutant (namely NH4+-N and chemical oxygen demand) removal efficiencies. By introducing both zero-valent iron and a static magnetic field, the power density increased four-fold to 9.2 mW/m2 and the internal resistance decreased by 26.7% to 467.4 Ω. Notably, static magnetic field decreased the relative abundance of electrochemically active bacteria (such as Romboutsia), while significantly enhancing species diversity. The permeability of the microbial cell membrane was improved, leading to a reduction in activation loss and internal resistance, thereby enhancing power generation capacity. Results showed that the addition of zero-valent iron and the applied magnetic field were beneficial to the pollutants removal and bioelectricity generation.

Fe2O3 micron particles are critical for electron transfer and the distribution of electrochemically active bacteria in soil MFCs

Fe2O3 plays a complex role in soil electron transfer. A microbial fuel cell (MFC) was constructed to drive the directional transfer of electrons in soil, and the results revealed that Fe2O3 acts first as a capacitor, intercepting and reserving the electrons produced by electrochemically active bacteria (EAB) in the soil, which leads to a decrease in hexachlorobenzene (HCB) removal efficiency with increasing proportions of Fe2O3 dosing (R2 = 0.85). The Fe2O3 then exerted its semiconductor properties in synergy with dissolved Fe2+ as an electron mediator to promote the flow of electrons in the soil. Power generation by the MFC was significantly and positively correlated with the concentration of dissolved Fe2+ (r = 0.51) and the Fe2O3 dosing proportion (r = 0.97). The higher HCB removal efficiency, spatial distribution of intercepted electrons, and abundance of electron transfer metabolic pathways confirmed that Fe2O3 promoted electron-flow fluxes in soil. Additionally, Geobacter sp., (direct electron transfer) and Pseudomonas sp., (indirect electron transfer) were the dominant electrochemically active bacteria in the anode and soil of MFC, respectively. In this study, both dissolved (Fe2+) and solid state (Fe2O3) electron mediators functioned as electron transporters in soil, we propose an internal “electron internet” of soil consisting of points and lines.

Novel and simplified method of producing microbial calcite powder for clayey soil stabilization

The green ground improvement technique utilizing microbial-induced calcite precipitation (MICP) has gained increasing interest. However, this technique is generally limited to stabilizing cohesion-less soil, as MICP poorly distributes in fine-grained soil with a low coefficient of permeability. Additionally, the method and information on producing MICP are not widely available, with few researchers reporting on optimum conditions and methods. Therefore, this study identified a new, simple approach for producing an ammonium carbonate supernatant, which can be precipitated into calcite and used to stabilize clayey soil. Based on the test results and optimization analysis, the proposed optimum conditions for producing the supernatant were Sporosarcina pasteurii as the selected bacteria and inoculation and incubation in a specific medium for 34 h to obtain a bacterial density of approximately 2.5 × 109 cells/mL. Then, the active bacteria were transferred to a 4M urea solution and cured for 8 h, after which the produced supernatant was precipitated into calcite and various percentages of admixtures were used to stabilize clayey soil specimens. The compressive strength of stabilized soil samples was investigated through a series of unconfined compression tests with various curing times and percentage of admixtures. The soil stabilized with calcite had higher ultimate compressive strengths than the untreated soil and its strength development over time was expressed by exponential function where the strength was expected to increase even after 56 days of curing. Microstructural analysis results indicated that the calcite particles filled the voids between soil particles and resulted in denser package of soil. However, the strength development of the calcite-treated soil was slow, with some elements of calcium silicate hydrate found in the calcite-treated soil specimens after curing for 56 days. The research outcomes will lead to potential implications for sustainable geotechnical and pavement engineering.

The impacts of ocean acidification, warming and their interactive effects on coral prokaryotic symbionts

BackgroundReef-building corals, the foundation of tropical coral reefs, are vulnerable to climate change e.g. ocean acidification and elevated seawater temperature. Coral microbiome plays a key role in host acclimatization and maintenance of the coral holobiont’s homeostasis under different environmental conditions, however, the response patterns of coral prokaryotic symbionts to ocean acidification and/or warming are rarely known at the metatranscriptional level, particularly the knowledge of interactive and persistent effects is limited. Using branching Acropora valida and massive Galaxea fascicularis as models in a lab system simulating extreme ocean acidification (pH 7.7) and/or warming (32 °C) in the future, we investigated the changes of in situ active prokaryotic symbionts community and gene expression of corals under/after (6/9 d) acidification (A), warming (H) and acidification–warming (AH) by metatranscriptome analysis with pH8.1, 26 °C as the control.ResultsA, H and AH increased the relative abundance of in situ active pathogenic bacteria. Differentially expressed genes (DEGs) involved in virulence, stress resistance, and heat shock proteins were up-regulated. Many DEGs involved in photosynthesis, carbon dioxide fixation, amino acids, cofactors and vitamins, auxin synthesis were down-regulated. A broad array of new DEGs involved in carbohydrate metabolism and energy production emerged after the stress treatment. Different response patterns of prokaryotic symbionts of massive G. fascicularis and branching A. valida were suggested, as well as the interactive effects of combined AH and persistent effects.ConclusionsThe metatranscriptome-based study indicates that acidification and/or warming might change coral’s in situ active prokaryotic microbial diversity and functional gene expression towards more pathogenic and destabilized coral-microbes symbioses, particularly combined acidification and warming show interactive effects. These findings will aid in comprehension of the coral holobiont’s ability for acclimatization under future climate change.

Three-Dimensional Printing of Ag Nanoparticle Meshes for Antibacterial Activity

Silver nanoparticles (Ag NPs) are decorated or encapsulated for use in antibacterial applications; however, their synthesis involves complex chemical processes. In this study, we developed a facile process for printing an Ag NP 3D microstructure to be applied as an antibacterial filter. The Ag NPs were printed in a mesh form using an aerodynamically focused nanomaterial (AFN) printing system. Unlike the conventional printing method, in the proposed method, the printed Ag NP mesh was peeled from a polydimethylsiloxane substrate. To examine this printing and peeling mechanism, molecular dynamics simulations were performed. In addition, characteristics of the Ag NP mesh were analyzed. The results of the analysis confirmed that the printed mesh retained the properties of Ag NPs. Meshes with various sizes and porosities were printed and their performance as an antibacterial filter was evaluated. Finally, a straw-shaped prototype water filter with three mesh layers was fabricated. A plate cultivated from a suspension filtered using this prototype contained zero active bacteria. This result indicates that the proposed Ag NP 3D printing process, which allows the preservation of antibacterial properties and has wide application scope, is an extensively viable process for manufacturing antibacterial microstructures.

Antibacterial activity of silver nanoparticles created by one step nanosecond Nd: YAG laser ablation in water

The pulsed laser ablation in liquid (PLAL) technique was used to successfully synthesise silver nanoparticles (Ag NPs). With the goal of controlling their size, a laser wavelength of 1064 nm was focused on the Ag bulk target immersed in distilled water in a glass vessel with different laser fluences. The effect of laser fluence, and thus Ag NPs concentration on the bacterial pathogenic was investigated. While the Fourier-transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) patterns confirm the presence of Ag NPs, UV–vis spectrophotometry revealed a significant absorption peak at around 405 nm, which is attributed to the obtained Ag NPs’ characteristic surface plasmon resonance (SPR) peak. The SPR peak shifted towards a shorter wavelength as the laser fluence was increased, indicating that the Ag NPs have reduced in size. The transmission electron microscopy and size distribution images of Ag NPs clearly showed the effects of laser fluence on size reduction of Ag NPs. Bacteria activity was effectively inhibited by the Ag NPs which are found to be more effective against Gram-negative (Escherichia coli) than Gram-positive strains (Streptococcus aureus). PLAL has proven to be an effective method for controlling the size of NPs, which can be used in a variety of applications.

Electrogenetic control of gene expression in Shewanella oneidensis MR-1 using Arc-dependent transcriptional promoters

Electrochemically active bacteria (EAB) are capable of electrically interacting with electrodes, enabling their application in bioelectrochemical systems (BESs). As the performance of BES is related to the metabolic activities of EAB, the development of methods to control their metabolic activities is important to facilitate BES applications. A recent study found that the EAB Shewanella oneidensis MR-1 uses the Arc system to regulate the expression of catabolic genes in response to electrode potentials, suggesting that a methodology for electrical control of gene expression in EAB, referred to as electrogenetics, can be developed by using electrode potential-responsive, Arc-dependent transcriptional promoters. Here, we explored Arc-dependent promoters in the genomes of S.oneidensis MR-1 and Escherichia coli to identify electrode potential-responsive promoters that are differentially activated in MR-1cells exposed to high- and low-potential electrodes. LacZ reporter assays using electrode-associated cells of MR-1 derivatives revealed that the activities of promoters located upstream of the E.coli feo gene (Pfeo) and the MR-1 nqrA2 (SO_0902) gene (Pnqr2) were significantly increased when S.oneidensis cells were exposed to electrodes poised at+0.7V and-0.4V (versus the standard hydrogen electrode), respectively. Additionally, we developed a microscopic system for in situ monitoring of promoter activity in electrode-associated cells and found that Pnqr2 activity was persistently induced in MR-1cells associated with an electrode poised at-0.4V. Our results indicate that these electrode potential-responsive promoters enable efficient regulation of gene expression in EAB, providing a molecular basis for the development of electrogenetics.

Metabolically active bacteria detected with click chemistry in low organic matter rainwater.

Rain contains encapsulated bacteria that can be transported over vast distances during relatively short periods of time. However, the ecological significance of bacteria in "precontact" rainwater-rainwater prior to contact with non-atmospheric surfaces-remains relatively undefined given the methodological challenges of studying low-abundance microbes in a natural assemblage. Here, we implement single-cell "click" chemistry in a novel application to detect the protein synthesis of bacteria in precontact rainwater samples as a measure of metabolic activity. Using epifluorescence microscopy, we find approximately 103-104 bacteria cells mL-1 with up to 7.2% of the observed cells actively synthesizing protein. Additionally, our measurement of less than 30 μM total organic carbon in the samples show that some rainwater bacteria can metabolize substrates in very low organic matter conditions, comparable to extremophiles in the deep ocean. Overall, our results raise new questions for the field of rainwater microbiology and may help inform efforts to develop quantitative microbial risk assessments for the appropriate use of harvested rainwater.

Bacterial extracellular electron transfer in plant and animal ecosystems.

Extracellular electron transfer (EET) is a bioelectrochemical process performed by electrochemically active bacteria (EAB) found in host-associated environments, including plant and animal ecosystems and fermenting plant- and animal-derived foods. Through direct or mediated electron transfer pathways, certain bacteria use EET to enhance ecological fitness with host-impacting effects. In the plant rhizosphere, electron acceptors support the growth of EAB such as Geobacter, cable bacteria, and some clostridia that can result changing iron and heavy metal uptake by plants. In animal microbiomes, EET is associated with diet-derived iron in the intestines of soil-dwelling termites, earthworms, and beetle larvae. EET is also associated with the colonization and metabolism of some bacteria in human and animal microbiomes, such as Streptococcus mutans in the mouth, Enterococcus faecalis and Listeria monocytogenes in the intestine, and Pseudomonas aeruginosa in the lungs. During the fermentation of plant tissues and bovine milk, lactic acid bacteria like Lactiplantibacillus plantarum and Lactococcus lactis may use EET to increase their growth and food acidification, as well as decrease environmental oxidation-reduction potential. Thus, EET is likely an important metabolic pathway for host-associated bacteria and has implications for ecosystem function, health and disease, and biotechnological applications.

Composition and transcriptional activity of oil reservoir microorganisms under different gas/liquid ratios

Microorganisms inhabited in oil reservoirs play a fundamental role in microbial enhanced oil recovery. Gas injection has been adopted as an alternative method in the tertiary oil recovery, but the influence of the gas injection on microbial composition in oil reservoir and its contribution to oil recovery still remained unclear. In this study, the effect of air injection on the microbial composition and transcriptional activity is investigated using a combination of the 16S rRNA gene amplicon sequencing, metagenomic and meta-transcriptomic analysis. Firmicutes were the main active bacteria in all samples and the proportion of Firmicutes increased with the rising of gas/liquid ratio in samples without additional treatment. The Bacillus was the dominant member of phylum Firmicutes. With the increase of gas-to-liquid ratios, the microbes showed higher overall transcription activities and propionate become an important metabolite. This research provides theoretical guidance for the activation of endogenous oil displacement microorganisms and sheds light on the industrial applications for exploitation of depleted reservoirs and the extension of the development life of oil reservoirs.

Baohe pill decoction treats diarrhea induced by high-fat and high-protein diet by regulating lactase-producing bacteria in intestinal mucosa.

This study aimed to investigate the effects of Baohe pill decoction (BPD) on microbial, lactase activity, and lactase-producing bacteria in the intestinal mucosa of mice with diarrhea induced by high-fat and high-protein diet (HFHPD). Thirty male Kunming (KM) mice were randomly divided into normal (NM), model (MD), and BPD groups. Diarrhea models were manufactured using HFHPD combined with a gavage of vegetable oil. At the end of modeling, the BPD group was given BPD (6.63 g·kg-1d-1) intervention twice daily for 3 d. The NM and MD groups were given equal amounts of sterile water. Subsequently, the intestinal mucosa of the mice was collected, one portion was used for microbial and lactase activity measurement, and the other portion was used for its lactase-producing bacterial characteristics by high-throughput sequencing technology. Our results showed that microbial and lactase activity of intestinal mucosa decreased significantly following diarrhea in mice (Pmicrobial < 0.05, Plactase < 0.001). After BPD intervention, microbial and lactase activity increased significantly (P < 0.01). The number of operational taxonomic units (OTUs), richness, and diversity index of lactase-producing bacteria increased in the BPD group compared to the MD group (P > 0.05), and the community structure were significant differences (P < 0.01). Compared to other groups, Saccharopolyspora, Rhizobium, Cedecea, and Escherichia were enriched in the BPD group. Notably, the relative abundance of the dominant lactase-producing genus Bifidobacterium decreased after BPD intervention. The mechanism of BPD in relieving diarrhea induced by HFHPD is closely related to the promotion of lactase activity in the intestinal mucosa, which may be achieved by regulating the structure of lactase-producing bacteria.

Synthesis, spectroscopic characterization, molecular studies, and biological evaluation of (E)-N'-((7-methyl-2-oxo-1,2-dihydroquinolin-3-yl)methylene)morpholine-4-carbothiohydrazide and some of its transition metal complexes

Novel Ni(II), Cu(II), Zn(II), Cd(II), and Pd(II) complexes (1–6) with (E)-N'-((7-methyl-2-oxo-1,2-dihydroquinolin-3-yl)methylene)morpholine-4-carbothiohydrazide ligand (HL) were prepared and characterized via different analytical and spectroscopic techniques. The spectral data showed that the ligand is bound with copper(II) chloride, zinc(II) chloride, cadmium(II) chloride, and potassium tetrachloropalladate(II) in its neutral thione form in complexes 2, 4, 5, and 6, respectively. Furthermore, the ligand was coordinated with nickel (II) chloride and copper(II) acetate in complexes 1 and 3 as a monobasic tridentate in its thiol form. Thermogravimetric studies were performed for the prepared compounds and the pyrolytic mechanism was proposed for some complexes. DFT, TD-DFT, and NBO calculations were achieved at the B3LYP/LanL2DZ level of theory. Computational studies showed that the investigated compounds have high hyperpolarizability values (β) suggesting their potential use in the creation of non-linear optical materials. Many bacterial and fungal strains were used to assess the ligand and its metal complexes' antibacterial activities. In general, metal complexes have been shown to possess a stronger antibacterial and antifungal effect thanthe free ligand. Complex 5 exhibited respectable antibacterial activity versus Gram-positive bacteria. Furthermore, Zn(II) and Cd(II), complexes 4 and 5 have shown excellent activity against Gram-negative bacteria. Complex 4 exhibited a superior antifungal activity against two types of tested fungi compared with other compounds and standard Ketoconazole. Molecular docking of the ligand and its complexes 1, 2, and 5 were performed against tyrosyl-tRNA synthetase. The more negative values of the binding energy indicate that complexes 1 and 5 have higher inhibition efficiency than the free ligand.

Accurate quantification on the change of some live pathogenic microbial flora in fermented feed

SummaryReal‐time monitoring of harmful bacteria in the process of feed fermentation is an important step to control and optimise feed quality. Real‐time quantitative polymerase chain reaction (qPCR) can effectively determine the total amount of pathogenic bacteria but does not distinguish between active and inactive bacteria. In this work, propidium monoazide dyes (PMA) were combined with qPCR technology to explore the changes of microflora during the fermentation of artificially contaminated feed. The results indicated that the Cycle Threshold (Ct) values of sample detected by PMA‐qPCR were all higher than the results of qPCR. PMA could effectively nullify the influence of dead bacteria in the detection of viable bacteria. It was found that the growth of Escherichia coli O157:H7, Shigella flexneri, and Staphylococcus aureus were inhibited during the fermentation process of soybean meal feed with the mortality rates were 99.89, 95.07 and 97.73%, respectively. However, the growth of beneficial bacteria were not affected by the presence of harmful bacteria after 60 days of storage. These results suggest that anaerobically fermented feed is a promising substitute for antibiotics in animal feed and using PMA‐qPCR for real‐time monitoring of harmful bacteria in fermented feed will further improve the safety risk assessment of fermented feed.

Functional characterization and molecular fingerprinting of potential phosphate solubilizing bacterial candidates from Shisham rhizosphere

Phosphate solubilizing bacteria (PSB) are important role players in plant growth promotion. In the present study, we aimed to screen the functionally active phosphate solubilizing bacteria (PSB) associated with Dalbergia sissoo Roxb. (Shisham) from different provenances. Screening for phosphate solubilization was done on Pikovskaya's agar, and 18 bacteria positive for the tri-calcium phosphate (Ca3(PO4)2 solubilization showing visible dissolution halo zones were identified. All 18 isolates showed zinc solubilization, indole acetic acid (IAA), siderophore, and hydrogen cyanide (HCN) production. The morphological and biochemical characterization with 16S rDNA gene-based phylogenetic analysis identified bacterial strains as belonging to the genus Pseudomonas, Klebsiella, Streptomyces, Pantoea, Kitasatospora, Micrococcus, and Staphylococcus. Among all the isolates, one of the isolates named L4, from Lacchiwala region was the most efficient P solubilizer with a high P solubilization index (4.75 ± 0.06) and quantitative P solubilization activity (891.38 ± 18.55 μg mL−1). The validation of phosphate solubilization activity of PSB isolates was done by amplification of the Pyrroloquinoline quinone (PQQ) genes, pqqA and pqqC. Based on this study, we have selected the bacterial strains which are efficient phosphate solubilizers and could be economical and eco-friendly in plant growth promotion, disease suppression, as an antioxidant, and for subsequent enhancement of yield.

Microbial fuel cell review: thermodynamic and infuencing factors, exoelectrogenic bacteria, anode and cathode configuration

AbstractOver the past 20 years the scientific community has become interested in microbial fuel cell microbial fuel cell (MFC) technology, because it offers the potential for the direct conversion of organic waste into power generation through microbially catalysed anodic and microbial–enzymatic–abiotic cathodic electrochemical reactions. Several facts about the technology are taken into account in this evaluation. A brief history of abiotic to biological fuel cells is presented, as well as a presentation of microbial fuel cells and a description of the concept of a microbial fuel cell in a broader range of derivative technologies known as bio‐electrochemical systems with biofilm formation, aerobic and anaerobic digestion of organic materials contained in the substrates and how electrons transfer from the surface of the biofilm to the outer circle. Microbial electrolysis cells, and electro‐synthesis cells are briefly discussed. MFC can be improved through the understanding of previous studies by defining the method of work and the theoretical foundations on which they are built. Moreover, the wide range of criteria that is likely to restrict their performance can be determined by providing a brief explanation of components that make them up. Thermodynamic and biotic factors and the mechanism of operation of these bio‐electrochemical systems need to be considered. A review of the various components that make up the MFC will be proposed, allowing for the illumination of the several scientific locks that continue to limit the technology's effectiveness. This review will provide a discussion of the mechanism of MFCs and provide details about the action of electrically active bacteria in the anode chamber through the generation of electroactive biofilms and the conversion of part of the energy available in the substrates, and this is one of renewable energy which is highlighted by researchers. © 2023 Society of Chemical Industry (SCI).

Integrating a manganese ores-filled module with a submerged plants cathode sediment fuel cell: In-situ remediation of ammonium pollution in surface water

Ammonium removal from contaminated surface water depends highly on electron acceptors like dissolved oxygen (DO), which was limited in eutrophic water bodies. In this study, a small ecological module was constructed with manganese ores (MO) and used to remove ammonium for the overlying water by integrating sediment microbial fuel cells (SMFC) and submerged plants. Nine different microcosms were operated to assess the pollutants removal performances. Compared with the 44.1 % of the control, ammonium removal of microcosms with MO addition increased to 79.1 %. Moreover, ammonium removal of the SMFC coupling system and submerged plant SMFC coupling system reached 83.3 % and 97.1 %, respectively. Besides, under the two coupling modes mentioned above, the degradation of chemical oxygen demand (COD) and the total organic carbon (TOC) was enhanced. The maximum power density was 390.63 mW/m3. The mass balance of nitrogen indicated the introduction of SMFC increased the contribution of denitrification to nitrogen removal. By contrast, plants promoted the release of oxygen and regulated community structure for intensifying simultaneous nitrification and denitrification (SND). Additionally, the effects of storage by substrates and sediments and plant uptake were also important. Heterotrophic and autotrophic denitrifying bacteria were enriched on the substrates around electrodes. Besides, electrochemically active bacteria (EAB) and Mn cycle related bacteria triggering the enhancement of nitrogen conversion. The Mn cycle in different valence states, electron transport between electrodes and substrates, and oxygen-producing submerged plants conspired to help excellent contaminant removal performance. This study promises a new thought for remediation of surface water and sediments in situ.