Roles of sulfate-reducing bacteria in sustaining the diversity and stability of marine bacterial community.

Microbes play central roles in ocean food webs and global biogeochemical processes. Yet, the information available regarding the highly diverse bacterial communities in these systems is not comprehensive. Here we investigated the diversity, assembly process, and species coexistence frequency of bacterial communities in seawater and sediment across ∼600 km of the eastern Chinese marginal seas using 16S rRNA gene amplicon sequencing. Our analyses showed that compared with seawater, bacterial communities in sediment possessed higher diversity and experienced tight phylogenetic distribution. Neutral model analysis showed that the relative contribution of stochastic processes to the assembly process of bacterial communities in sediment was lower than that in seawater. Functional prediction results showed that sulfate-reducing bacteria (SRB) were enriched in the core bacterial sub-communities. The bacterial diversities of both sediment and seawater were positively associated with the relative abundance of SRB. Co-occurrence analysis showed that bacteria in seawater exhibited a more complex interaction network and closer co-occurrence relationships than those in sediment. The SRB of seawater were centrally located in the network and played an essential role in sustaining the complex network. In addition, further analysis indicated that the SRB of seawater helped maintain the high stability of the bacterial network. Overall, this study provided further comprehensive information regarding the characteristics of bacterial communities in the ocean, and provides new insights into keystone taxa and their roles in sustaining microbial diversity and stability in ocean.

Bioinspired design of Na-ion conduction channels in covalent organic frameworks for quasi-solid-state sodium batteries.

Solid polymer electrolytes are considered among the most promising candidates for developing practical solid-state sodium batteries. However, moderate ionic conductivity and narrow electrochemical windows hinder their further application. Herein, inspired by the Na+/K+ conduction in biological membranes, we report a (-COO-)-modified covalent organic framework (COF) as a Na-ion quasi-solid-state electrolyte with sub-nanometre-sized Na+ transport zones (6.7-11.6 Å) created by adjacent -COO- groups and COF inwalls. The quasi-solid-state electrolyte enables selective Na+ transport along specific areas that are electronegative with sub-nanometre dimensions, resulting in a Na+ conductivity of 1.30×10-4 S cm-1 and oxidative stability of up to 5.32 V (versus Na+/Na) at 25 ± 1 °C. Testing the quasi-solid-state electrolyte in Na||Na3V2(PO4)3 coin cell configuration demonstrates fast reaction dynamics, low polarization voltages, and a stable cycling performance over 1000 cycles at 60 mA g-1 and 25 ± 1 °C with a 0.0048% capacity decay per cycle and a final discharge capacity of 83.5 mAh g-1.

Dual Molecules Cooperatively Confined In-Between Edge-oxygen-rich Graphene Sheets as Ultrahigh Rate and Stable Electrodes for Supercapacitors.

Noncovalent modification of carbon materials with redox-active organic molecules has been considered as an effective strategy to improve the electrochemical performance of supercapacitors. However, their low loading mass, slow electron transfer rate, and easy dissolution into the electrolyte greatly limit further practical applications. Herein, this work reports dual molecules (1,5-dihydroxyanthraquinone (DHAQ) and 2,6-diamino anthraquinone (DAQ)) cooperatively confined in-between edge-oxygen-rich graphene sheets as high-performance electrodes for supercapacitors. Cooperative electrostatic-interaction on the edge-oxygen sites and π-π interaction in-between graphene sheets lead to the increased loading mass and structural stability of dual molecules. Moreover, the electron tunneling paths constructed between edge-oxygen groups and dual molecules can effectively boost the electron transfer rate and redox reaction kinetics, especially at ultrahigh current densities. As a result, the as-obtained electrode exhibits a high capacitance of 507 F g-1 at 0.5 A g-1 , and an unprecedented rate capability (203 F g-1 at 200 A g-1 ). Moreover, the assembled symmetrical supercapacitor achieves a high energy density of 17.1 Wh kg-1 and an ultrahigh power density of 140 kW kg-1 , as well as remarkable stability with a retention of 86% after 50 000 cycles. This work may open a new avenue for the efficient utilization of organic materials in energy storage and conversion.

Response of Microbial Communities on Cathode with Different Potentials in a Single-Chamber Reactor.

Microbes use both organic and inorganic compounds as electron donors, with different electronic potentials, to produce energy required for growth in environments. Conventional studies on the effects of different electron donors on microbial community has been extensively studied with a set cathode potential. However, it remains under-researched how a microbial community response to the different redox potentials in different environments. Here, we incubated a lake sediment in a single-chamber reactor equipped with three working electrodes, i.e., with potentials of - 0.29 V, - 0.05 V versus standard hydrogen electrode and open-circuit, respectively. Results reveal that the structure of bacterial communities was highly similar for all closed-circuit electrodes (- 0.29 V, - 0.05 V), while differing significantly from those on open-circuit electrodes. We also show that specific bacteria were preferentially enriched by different electrode potentials, i.e., Pseudomonas and Rhodobacter preferentially grew on - 0.05 V and - 0.29 V cathode potentials, Azospirillum and Bosea preferentially grew on - 0.05 V; while Ferrovibrio, Hydrogenophaga, Delftia, and Sphingobium preferentially grew on - 0.29 V. In addition, microorganisms selectively enriched on open-circuit electrodes possess higher connectivity and closer relationship than microorganisms selectively enriched on closed-circuit electrode.

Controllable Substitution of S Radicals on Triazine Covalent Framework to Expedite Degradation of Polysulfides.

Lithium-sulfur (Li-S) batteries are facing a significant barrier due to the diffusion of intermediate redox species. Although some S doped covalent framework cathodes have been reported with outstanding reversibility, the low content of sulfur (less than 30%) limits the practical applications. To overcome the issue, the sulfur and nitrogen co-doped covalent compounds (S-NC) as a host-type cathode have been developed through the radical transfer process during thermal cracking amino groups on the precursor, and then plentiful positively charged sulfur radicals can be controllably introduced. The experimental characterization and DFT theoretical calculation certificate that the sulfur radicals in S-NC/S can expedite redox reactions of intermediate polysulfides to impede their dissolution. Moreover, the energy barriers during ions transfer also obviously decreased after introducing S radicals, which lead to improved rate performance.

Improvement of Surface-Enhanced Raman Scattering Method for Single Bacterial Cell Analysis.

Surface-enhanced Raman scattering (SERS) is a useful tool for label-free analysis of bacteria at the single cell level. However, low reproducibility limits the use of SERS. In this study, for the sake of sensitive and reproducible Raman spectra, we optimized the methods for preparing silver nanoparticles (AgNPs) and depositing AgNPs onto a cell surface. We found that fast dropwise addition of AgNO3 into the reductant produced smaller and more stable AgNPs, with an average diameter of 45 ± 4 nm. Compared with that observed after simply mixing the bacterial cells with AgNPs, the SERS signal was significantly improved after centrifugation. To optimize the SERS enhancement method, the centrifugal force, method for preparing AgNPs, concentration of AgNPs, ionic strength of the solution used to suspend the cells, and density of the cells were chosen as impact factors and optimized through orthogonal experiments. Finally, the improved method could generate sensitive and reproducible SERS spectra from single Escherichia coli cells, and the SERS signals primarily arose from the cell envelope. We further verified that this optimal method was feasible for the detection of low to 25% incorporation of 13C isotopes by the cells and the discrimination of different bacterial species. Our work provides an improved method for generating sensitive and reproducible SERS spectra.

Intrinsic Defect-Rich Hierarchically Porous Carbon Architectures Enabling Enhanced Capture and Catalytic Conversion of Polysulfides.

Despite their promising potential, the real performance of lithium-sulfur batteries is still heavily impeded by the notorious shuttle behavior and sluggish conversion of polysulfides. Complex structures with multiple components have been widely employed to address these issues by virtue of their strong polarity and abundant surface catalytic sites. Nevertheless, the tedious constructing procedures and high cost of these materials make the exploration of alternative high-performance sulfur hosts increasingly important. Herein, we report an intrinsic defect-rich hierarchically porous carbon architecture with strong affinity and high conversion activity toward polysulfides even at high sulfur loading. Such an architecture can be prepared using a widely available nitrogen-containing precursor through a simple yet effective in situ templating strategy and subsequent nitrogen removal procedure. The hierarchical structure secures a high sulfur loading, while the intrinsic defects strongly anchor the active species and boost their chemical conversion because of the strong polarity and accelerated electron transfer at the defective sites. As a result, the lithium-sulfur batteries with this carbon material as the sulfur host deliver a high specific capacity of 1182 mAh g-1 at 0.5 C, excellent cycling stability with a capacity retention of 70% after 500 cycles, and outstanding rate capability, one of the best results among pure carbon hosts. The strategy suggested here may rekindle interest in exploring the potential of pure carbon materials for lithium-sulfur batteries as well as other energy storage devices.

EB virus-positive tumors are inhibited by rBCG expressing hGM-CSF and LMP2A.

For the development of safe and effective EBV (Epstein-Barr virus) vaccines, the Ag85A signal peptide from M. tuberculosis H37Rv was used to construct a recombinant secretory BCG (Bacillus Chalmette-Guérin) plasmid. The Ag85A gene, fused to the EBV LMP2A (latent membrane protein) and hGM-CSF (human granulocyte/macrophage colony-stimulating factor) genes, was inserted into the pMV261 vector (secretory BCG plasmid). The expression levels of the hGM-CSF and LMP2A proteins in rBCG (recombinant BCG) were measured by Western blot analysis. Humoral immunity, cellular immunity, and antitumor effects were determined by a series of experiments. The recombinant pMVGCA plasmid effectively expressed GCA (hGM-CSF and LMP2A fusion protein) in BCG after transformation, and the rBCG proteins were recognized by antibodies against hGM-CSF and LMP2A. Six weeks after immunization, the maximum dose of rBCG resulted in antibody titers of 1:19,800 (hGM-CSF antibody) and 1:21,800 (LMP2A antibody). When the effector:target ratio was 40:1, specific lysis was maximal and approximately two times stronger than that in mice immunized with the control. Tumorigenicity was lower in the rBCG treatment group, with a tumor inhibition rate of 0.81 ± 0.09 compared with the control groups. EB virus-positive tumors are inhibited by rBCG expressing an hGM-CSF and LMP2A fusion protein.

Response of Propionate-Degrading Methanogenic Microbial Communities to Inhibitory Conditions.

Propionate is a crucial intermediate during methane fermentation. Investigating the effects of different kinds of inhibitors on the propionate-degrading microbial community is necessary to develop countermeasures for improving process stability. In the present study, under inhibitory conditions (acetate, propionate, sulfide, and ammonium addition), the dynamic changes of the propionate-degrading microbial community from a mesophilic chemostat fed with propionate as the sole carbon source were investigated using high-throughput sequencing of 16S rRNA. Sulfide and/or ammonia inhibited specific species in the microbial community. Compared with Syntrophobacter, Smithella was more resistant to inhibition by sulfide and/or ammonia. However, Syntrophobacter demonstrated greater tolerance than Smithella under acid inhibition conditions. Some genera that had close phylogenetic relationships and similar functions showed similar responses to different inhibitors.

Natural Extracellular Electron Transfer Between Semiconducting Minerals and Electroactive Bacterial Communities Occurred on the Rock Varnish.

Rock varnish is a thin coating enriched with manganese (Mn) and iron (Fe) oxides. The mineral composition and formation of rock varnish elicit considerable attention from geologists and microbiologists. However, limited research has been devoted to the semiconducting properties of these Fe/Mn oxides in varnish and relatively little attention is paid to the mineral-microbe interaction under sunlight. In this study, the mineral composition and the bacterial communities on varnish from the Gobi Desert in Xinjiang, China were analyzed. Results of principal components analysis and t-test indicated that more electroactive genera such as Acinetobacter, Staphylococcus, Dietzia, and Pseudomonas gathered on varnish bacterial communities than on substrate rock and surrounding soils. We then explored the culture of varnish, substrate and soil samples in media and the extracellular electron transfer (EET) between bacterial communities and mineral electrodes under light/dark conditions for the first time. Orthogonal electrochemical experiments demonstrated that the most remarkable photocurrent density of 6.1 ± 0.4 µA/cm2 was observed between varnish electrode and varnish microflora. Finally, based on Raman and 16S rRNA gene-sequencing results, coculture system of birnessite and Pseudomonas (the major Mn oxide and a common electroactive bacterium in varnish) was established to study underlying mechanism. A steadily growing photocurrent (205 µA at 100 h) under light was observed with a stable birnessite after 110 h. However, only 47 µA was generated in the dark control and birnessite was reduced to Mn2+ in 13 h, suggesting that birnessite helped deliver electrons instead of serving as an electron acceptor under light. Our study demonstrated that electroactive bacterial communities were positively correlated with Fe/Mn semiconducting minerals in varnish, and diversified EET process occurred on varnish under sunlight. Overall, these phenomena may influence bacterial-community structure in natural environments over time.

Regulation of iNOS on Immune Cells and Its Role in Diseases.

In recent years, there have been many studies on the function of nitric oxide synthase (NOS) in experimental animals and humans. This review analyzes and explores the relationship between inducible nitric oxide synthase (iNOS) and T cells, macrophages, and dendritic cell et al. differentiation using data based on laboratory research, highlighting recent NOS laboratory research. Our insights into research prospects and directions are also presented.

Purification of eutrophic water containing chlorpyrifos by aquatic plants and its effects on planktonic bacteria.

In this study, the removal of nutrients and chlorpyrifos as well as shifts of planktonic bacterial communities in constructed microcosms were investigated to evaluate the influence of Phragmites australis, Nymphaea alba, and Myriophyllum verticillatum, and their combination, on the restoration of eutrophic water containing chlorpyrifos. Plant-treated groups showed a higher pollutant removal rate than did no-remediation controls, indicating that treatment with plants is effective at remediation of eutrophic water containing chlorpyrifos. Different plants showed different performance on the remediation of eutrophic water, e.g., P. australis manifested stronger capacity for removal of sediment chlorpyrifos. This finding indicated that an appropriate plant combination is needed to deal with complex wastewater. During the treatments, the planktonic bacterial communities were influenced by the concentrations of nutrients and pollutants. The changes of composition of bacterial communities indicated a strong correlation between the bacterial communities and the concentrations of pollutants. The plants also influenced the planktonic bacterial communities, especially at the early phase of treatments. For example, P. australis increased the abundance of Limnohabitans and Nevskia significantly and decreased the abundance of Devosia, Luteolibacter, Methylibium, and Caulobacter significantly. The abundance of Hydrocarboniphaga significantly increased in N. alba-treated microcosms, whereas in M. verticillatum-treated microcosms, the abundance of Limnohabitans and Bdellovibrio significantly increased. Our results suggest that the planktonic bacterial communities may be altered during phytoremediation, and the functions of the affected bacteria should be concerned.

Efficacy of recombinant adenovirus expressing a fusion gene from GM-CSF and Epstein-Barr virus LMP2A in a mouse tumor model.

In this study, purified GM-CSF and LMP2A mRNAs were amplified by PCR. Then, the GM-CSF and LMP2A sequences were connected by the polypeptide linker (Gly4Ser)3 using gene splicing by overlap extension. The constructed fusion gene GC2A was inserted into the adenovirus vector. Then the recombinant vector was introduced into HEK 293T cells by calcium phosphate transfection to package the adenovirus. The levels of antibodies against the GM-CSF and LMP2Afusion proteins were measured by ELISA, and the CTL activity of the mouse splenic lymphocytes was determined by lactate dehydrogenase (LDH) release assay. Immunotherapy of mouse tumor (EBV-positive epithelial tumor cell line (GT39)) tissues was performed, and their morphologies were assessed. Finally, the data of each group were analyzed using SPSS 11.5 statistical software. The recombinant adenovirus could replicate in HEK 293Tcells and induce humoral and cellular immune responses in the mice. The maximum dose resulted in an antibody titer of 18500 (184.5 ± 8.7 pg/ml). At an effector: target ratio of 40:1, maximum specific lysis was observed which was approximately three times that detected in the control immunized mice. The tumor inhibition rate was approximately 76% compared with the control groups, indicating the presence of significant differences among the groups. Tumor-infiltrating lymphocytes were detected by hematoxylin-eosin (HE) staining. The recombinant adenovirus induced humoral and cellular immune responses and inhibited tumor growth in mice. It provided a theoretical basis and candidate vaccine for further preclinical trials.

Molecular Characterization of Wild Type Measles Virus from Adult Patients in Northern China, 2014.

OBJECTIVES: In this study, we studied the N and H genes from wild type measles viruses (MeVs) isolated during the 2013-2014 outbreak. METHODS: Clinical samples were collected, and the genotyping, phylogenetic analysis were performed. RESULTS: The vaccination rate of the study population was 4%. Genotype H1a was the predominant genotype. Wild type viruses were classified into clusters A and B, C and may have different origins. N-450 sequences from wild type viruses were highly homologous with, and likely evolved from MeVs circulating in Tianjing and Henan in 2012. MVs/Shenyang.CHN/18.14/3 could have evolved from MeVs from Liaoning, Beijing, Hebei, Heilongjiang, Henan, Jilin, and Tianjin. Our data suggested that one or more of the same viruses circulated between Beijing, Shenyang, Hong Kong, Taiwan and Berlin. CONCLUSIONS: Important factors contributing to outbreaks could include weak vaccination coverage, poor vaccination strategies, and migration of adult workers between cities, countries, and from rural areas to urban areas.

Process Performance and Bacterial Community Structure Under Increasing Influent Disturbances in a Membrane-Aerated Biofilm Reactor.

The membrane-aerated biofilm reactor (MABR) is a promising municipal wastewater treatment process. In this study, two cross-flow MABRs were constructed to explore the carbon and nitrogen removal performance and bacterial succession, along with changes of influent loading shock comprising flow velocity, COD, and NH4-N concentrations. Redundancy analysis revealed that the function of high flow velocity was mainly embodied in facilitating contaminants diffusion and biosorption rather than the success of overall bacterial populations (p > 0.05). In contrast, the influent NH4-N concentration contributed most to the variance of reactor efficiency and community structure (p < 0.05). Pyrosequencing results showed that Anaerolineae, and Beta- and Alphaproteobacteria were the dominant groups in biofilms for COD and NH4-N removal. Among the identified genera, Nitrosomonas and Nitrospira were the main nitrifiers, and Hyphomicrobium, Hydrogenophaga, and Rhodobacter were the key denitrifiers. Meanwhile, principal component analysis indicated that bacterial shift in MABR was probably the combination of stochastic and deterministic processes.

Development of a rat model of D-galactosamine/lipopolysaccharide induced hepatorenal syndrome.

AIM: To develop a practical and reproducible rat model of hepatorenal syndrome for further study of the pathophysiology of human hepatorenal syndrome. METHODS: Sprague-Dawley rats were intravenously injected with D-galactosamine and lipopolysaccharide (LPS) via the tail vein to induce fulminant hepatic failure to develop a model of hepatorenal syndrome. Liver and kidney function tests and plasma cytokine levels were measured after D-galactosamine/LPS administration, and hepatic and renal pathology was studied. Glomerular filtration rate was detected in conscious rats using micro-osmotic pump technology with fluorescein isothiocyanate-labelled inulin as a surrogate marker. RESULTS: Serum levels of biochemical indicators including liver and kidney function indexes and cytokines all significantly changed, especially at 12 h after D-galactosamine/LPS administration [alanine aminotransferase, 3389.5 ± 499.5 IU/L; blood urea nitrogen, 13.9 ± 1.3 mmol/L; Cr, 78.1 ± 2.9 µmol/L; K(+), 6.1 ± 0.5 mmol/L; Na(+), 130.9 ± 1.9 mmol/L; Cl(-), 90.2 ± 1.9 mmol/L; tumor necrosis factor-α, 1699.6 ± 599.1 pg/mL; endothelin-1, 95.9 ± 25.9 pg/mL; P < 0.05 compared with normal saline control group]. Hepatocyte necrosis was aggravated gradually, which was most significant at 12 h after treatment with D-galactosamine/LPS, and was characterized by massive hepatocyte necrosis, while the structures of glomeruli, proximal and distal tubules were normal. Glomerular filtration rate was significantly decreased to 30%-35% of the control group at 12 h after D-galactosamine/LPS administration [Glomerular filtration rate (GFR)1, 0.79 ± 0.11 mL/min; GFR2, 3.58 ± 0.49 mL/min·kgBW(-1); GFR3, 0.39 ± 0.99 mL/min·gKW(-1)]. The decreasing timing of GFR was consistent with that of the presence of hepatocyte necrosis and liver and kidney dysfunction. CONCLUSION: The joint use of D-galactosamine and LPS can induce liver and kidney dysfunction and decline of glomerular filtration rate in rats which is a successful rat model of hepatorenal syndrome.