Aerobic denitrifying bacterial-fungal consortium mediating nitrate removal: Dynamics, network patterns and interactions.

In recent years, nitrogen removal by mixed microbial cultures has received increasing attention owing to cooperative metabolism. A natural bacterial-fungal consortium was isolated from mariculture, which exhibited an excellent aerobic denitrification capacity. Under aerobic conditions, nitrate removal and denitrification efficiencies were up to 100% and 44.27%, respectively. High-throughput sequencing and network analysis suggested that aerobic denitrification was potentially driven by the co-occurrence of the following bacterial and fungal genera: Vibrio, Fusarium, Gibberella, Meyerozyma, Exophiala and Pseudoalteromonas, with the dominance of Vibrio and Fusarium in bacterial and fungal communities, respectively. In addition, the isolated consortium had a high steady aerobic denitrification performance in our sub-culturing experiments. Our results provide new insights on the dynamics, network patterns and interactions of aerobic denitrifying microbial consortia with a high potential for new biotechnology applications.

An Electrochromic Nickel Phosphate Film for Large-Area Smart Window with Ultra-Large Optical Modulation.

Exploring materials with high electrochemical activity is of keen interest for electrochemistry-controlled optical and energy storage devices. However, it remains a great challenge for transition metal oxides to meet this feature due to their low electron conductivity and insufficient reaction sites. Here, we propose a type of transition metal phosphate (NiHPO4·3H2O, NHP) by a facile and scalable electrodeposition method, which can achieve the capability of efficient ion accommodation and injection/extraction for electrochromic energy storage applications. Specifically, the NHP film with an ultra-high transmittance (approach to 100%) achieves a large optical modulation (90.8% at 500 nm), high coloration efficiency (75.4 cm2 C-1 at 500 nm), and a high specific capacity of 47.8 mAh g-1 at 0.4 A g-1. Furthermore, the transformation mechanism of NHP upon electrochemical reaction is systematically elucidated using in situ and ex situ techniques. Ultimately, a large-area electrochromic smart window with 100 cm2 is constructed based on the NHP electrode, displaying superior electrochromic energy storage performance in regulating natural light and storing electrical charges. Our findings may open up new strategies for developing advanced electrochromic energy storage materials and smart windows.

Metagenomic exploration of antibiotic resistance genes and their hosts in aquaculture waters of the semi-closed Dongshan Bay (China).

In marine environments, increasing occurrence and numbers of microbial Antibiotic Resistance Gene (ARG) subtypes, especially of new beta-lactamases, have received lots of attention in recent years. Updated databases with novel developed tools provide new opportunities to obtain more comprehensive ARG profiles as well as ARG-carrying hosts. Yet, ARGs in human-associated marine aquaculture environments, e.g. in China, remains largely unknown. Using metagenomic data, we revealed high numbers of Multi-drug Resistance, beta-lactamase and aminoglycoside genes throughout the year. Thereby, Alpha- and Gamma-proteobacteria were assigned to the majority of beta-lactamase-carrying hosts. From Metagenome-assembled genomes, three blaF-like beta-lactamases (91.7-94.7% identity with beta-lactamase from Mycobacterium fortuitum (blaF)) were exclusively observed in an unclassified Mycobacterium genus. Notably, other new beta-lactamases, VMB-1-like (n = 3) (58.5-67.4% identity to Vibrio metallo-beta-lactamase 1 (VMB-1)), were found in Gammaproteobacteria. Additionally, 175 Multi-drug Resistant Organisms possessed at least 3 ARG subtypes, and seven of the potentially pathogenic genera (n = 17) were assigned to Gammaproteobacteria. These results, together with high-risk ARGs (e.g. tetM, dfrA14 and dfrA17), provide hosts and new beta-lactamases of ARGs in Chinese coastal aquaculture.

Disentangling the abundance and structure of Vibrio communities in a semi-enclosed Bay with mariculture (Dongshan Bay, Southern China).

The genus Vibrio contains a diverse group of heterotrophic bacteria, which are members of ubiquitous and abundant microbial communities in coastal ecosystems. Vibrio has been frequently found in a wide range of marine environments either by employing Vibrio-specific 16S rRNA sequencing or culturing methods. A combination of molecular and cultivation-dependent methods was developed to more precisely discriminate between different members of the genus Vibrio in seawater. This newly developed assay was subsequently applied to characterize Vibrio community composition in surface water at 18 mariculture sites. It Substantially improved the taxonomic resolution of Vibrio species when compared to traditional 16S rRNA analysis. Our qPCR and cultivation analyses revealed that average Vibrio abundance (Vibrio 16S rRNA gene copy numbers: 3.46 × 106 to 6.70 × 106 copies L-1) and live cell numbers (5.65 × 104-5.75 × 105 cfu mL-1) are significantly related to pH. Total bacteria and Vibrio-specific 16S rRNA metabarcode sequenceing resulted in a total of 10 and 32 operational taxonomic units (OTUs), respectively, and 15 Vibrio species were identified by targeted cultivation of Vibrio strains, with Vibrio fortis and V. brasiliensis dominating in the mariculture areas. The purpose of this study was to combine several analytical methods to improve current sequence-based Vibrio community surveys, and to prove for the effectiveness of this methodological approach comprehensively testing for Vibrio dynamics in different coastal environments.

Spatiotemporal Dynamics of Vibrio Communities and Abundance in Dongshan Bay, South of China.

The Vibrio genus inhabit estuarine and marine ecosystem throughout the world and can cause severe infections in humans and animals. Previous studies have demonstrated the dynamics of Vibrio at both community and population levels and assessed the close relationship between environmental factors and Vibrio diversity and abundance, such as temperature, salinity, and dissolved oxygen. It is also generally believed that aquaculture is the fastest-growing food sector, which is also applying great environmental impacts on microbial communities in aquatic ecosystems. However, our understanding of the spatiotemporal quantification of Vibrio throughout the four seasons in the aquaculture zone and response to environmental factors remains poor. To explore the spatiotemporal distribution and abundance of the Vibrio community with their related environmental factors and detect the relationships among them, we collected 10 seawater sites spanning four seasons across the whole year in Dongshan Bay for investigating the Vibrio community dynamics. Marked differences in diversity and abundance of the Vibrio community were observed between seasons, which were mainly driven by temperature, dissolved oxygen, nitrate, and nitrite. qPCR analysis showed that Vibrio abundance was most abundant in the summer (5.37 × 106 copies/L), compared with the autumn (4.58 × 106 copies/L), spring (1.18 × 106 copies/L), and winter (1.55 × 104 copies/L). A total of 22 Vibrio operational taxonomic units (OTUs) and 28 species were identified by universal bacteria 16S rRNA gene and cultivation methods, with Vibrio fortis the dominant in these aquaculture areas. To summarize, our present study is one of the few studies to research the occurrence of Vibrio in marine aquaculture of South China, and the results indicate that Vibrio are widely distributed in aquaculture environment and that a further risk assessment is needed to be conducted.

Fungal diversity in deep-sea sediments from the Magellan seamounts as revealed by a metabarcoding approach targeting the ITS2 regions.

Recent reports have revealed diverse and abundant fungal communities in the deep-sea biosphere, while their composition, distribution, and variations in seamount zones are poorly understood. Using a metabarcoding approach targeting the ITS2 regions, we present the structure of the fungal community in 18 sediment samples from the Magellan seamount area of the northwest Pacific. A total of 1,979 fungal OTUs was obtained, which were taxonomically assigned to seven phyla, 17 classes, 43 orders, 7 families, and 98 genera. The majority of these OTUs were affiliated to Basidiomycota (873 OTUs, 44.11% of total OTUs) and Ascomycota (486 OTUs, 24.56% of total OTUs), followed by other five minor phyla (Mortierellomycota, Chytridiomycota, Mucoromycota, Glomeromycota, and Monoblepharidomycota). Sordriomycetes is the most abundant class, followed by Eurotiomycetes, and Dothideomycetes. Five genera were common in most of the samples, including worldwide reported genera Aspergillus, Cladosporium, Fusarium, Chaetomium, and Penicillium. The environmental data we collected (sampling depth, sampling location latitude and longitude, organic carbon content, and organic nitrogen content in the sediment) had no significant influence on the composition and distribution of fungal communities. Our findings provide valuable information for understanding the distribution and potential ecological functions of fungi in the deep-sea sediments of the Magellan seamounts.

Fungal diversity in deep-sea sediments from Magellan seamounts environment of the western Pacific revealed by high-throughput Illumina sequencing.

There are lots of seamounts globally whose primary production is disproportionally greater than the surrounding areas. Compared to other deep-sea environments, however, the seamounts environment is relatively less explored for fungal diversity. In the present study, we explored the fungal community structure in deep-sea sediments from four different stations of the Magellan seamounts environment by using high-throughput sequencing of the ITS1 region. A total of 1,897,618 ITS1 sequences were obtained. Among these sequences, fungal ITS1 sequences could be clustered into 1,662 OTUs. The majority of these sequences belonged to Ascomycota. In the genera level, the most abundant genus was Mortierella (4.79%), which was reported as a common fungal genus in soil and marine sediments, followed by Umbelopsis (3.80%), Cladosporium (2.98%), Saccharomycopsis (2.53%), Aspergillus (2.42%), Hortaea (2.36%), Saitozyma (2.20%), Trichoderma (2.12%), Penicillium (2.11%), Russula (1.86%), and Verticillium (1.40%). Most of these recovered genera belong to Ascomycota. The Bray-Curtis analysis showed that there was 37 to 85% dissimilarity of fungal communities between each two sediment samples. The Principal coordinates analysis clearly showed variations in the fungal community among different sediment samples. These results suggested that there was a difference in fungal community structures not only among four different sampling stations but also for different layers at the same station. The depth and geographical distance significantly affect the fungal community, and the effect of depth and geographical distance on the structure of the fungal community in the Magellan seamounts is basically same. Most of the fungi were more or less related to plants, these plant parasitic/symbiotic/endophytic fungi constitute a unique type of seamounts environmental fungal ecology, different from other marine ecosystems.

A novel self-assembled-derived 1D MnO2@Co3O4 composite as a high-performance Li-ion storage anode material.

Manganese dioxide (MnO2) is a high-performance anodic material and applied widely in lithium-ion batteries (LIBs). However, some intrinsic limitations originate from the low ionic conductivity, high polarization, and severe volume expansion of this type of material. In this work, we generated a one-dimensional porous MnO2@Co3O4 composite from a MnOOH@ZIF-67 precursor, which is synthesized via a self-assembly strategy. The one-dimensional porous structure provided more active sites and shorter-ion/electron-diffusion distance, thereby enabling higher Li+ storage capacity and better rate capability than a transition metal oxide alone. The Co3O4 coating buffered the volume change during Li+ insertion/extraction, leading to increased cycling stability of the electrode. When evaluated as the anode of LIBs, MnO2@Co3O4 exhibited a reversible capacity of 647 mA h g-1 at 2000 mA g-1 after 400 cycles. This excellent performance indicated that the MnO2@Co3O4 material could be an attractive potential candidate for Li+ storage.

A two-dimensional zinc(II)-based metal-organic framework for fluorometric determination of ascorbic acid, chloramphenicol and ceftriaxone.

A two-dimensional zinc(II)-based metal-organic framework [Zn • (BA) • (BBI)] was synthesized from 1,2-benzenediacetic acid and 1,1'-(1,4-butanediyl) bis(imidazole) via a solvothermal reaction. The crystal exhibits good chemical stability in the pH range from 2 to 12, and strong fluorescence with excitation/emission maxima of 270/290 nm. The crystal is shown to by a viable fluorescent probe for the detection of ascorbic acid (AA) and the antibiotics chloramphenicol (CHL) and ceftriaxone (CRO). Fluorescence intensity of crystal dispersion is significantly quenched with increasing concentrations of AA/CHL/CRO. Quenching occurs even in the presence of other substances. The assay is fast (5 s) and has a low detection limit (1.6 ppb for AA, 12 ppb for CHL and 3.9 ppb for CRO). The crystal still has a good quenching effect on AA/CHL/CRO after washing and using for five times. The response of the probe is related to the interplay between the MOF and analytes via energy absorption competition. Graphical abstractSchematic diagram of preparing Zn • (BA) • (BBI) and responding to target analytes. BA: 1,2-phenyldiacetic acid; BBI: 1,1'-(1,4-butanediyl)bis(imidazole); Zn • (BA) • (BBI): Crystal chemical formula.

A Cd-MOF as a fluorescent probe for highly selective, sensitive and stable detection of antibiotics in water.

Recently, the pollution and damage caused by antibiotics in water have aroused serious concerns. In this situation, it is extremely important to develop a highly effective approach to detect antibiotics in water. In this contribution, we built a Cd-MOF material with stable fluorescence properties, using bbi = 1,4-bis(2-methyl-imidazol-1-yl)butane and H2L = 1,2-phenylenediacetic acid as organic ligands and Cd(NO3)2·4H2O as the metal node. The highly selective response of this MOF probe to ceftriaxone sodium (an antibiotic) can reach up to the ppb level in water, along with a fast response time, acid and alkali resistance, and anti-interference ability.

Dynamic Response of Graphitic Flakes in Nematic Liquid Crystals: Confinement and Host Effect.

Electric field-induced reorientation of suspended graphitic (GP) flakes and its relaxation back to the original state in a nematic liquid crystal (NLC) host are of interest not only in academia, but also in industrial applications, such as polarizer-free and optical film-free displays, and electro-optic light modulators. As the phenomenon has been demonstrated by thorough observation, the detailed study of the physical properties of the host NLC (the magnitude of dielectric anisotropy, elastic constants, and rotational viscosity), the size of the GP flakes, and cell thickness, are urgently required to be explored and investigated. Here, we demonstrate that the response time of GP flakes reorientation associated with an NLC host can be effectively enhanced by controlling the physical properties. In a vertical field-on state, higher dielectric anisotropy and higher elasticity of NLC give rise to quicker reorientation of the GP flakes (switching from planar to vertical alignment) due to the field-induced coupling effect of interfacial Maxwell-Wagner polarization and NLC reorientation. In a field off-state, lower rotational viscosity of NLC and lower cell thickness can help to reduce the decay time of GP flakes reoriented from vertical to planar alignment. This is mainly attributed to strong coupling between GP flakes and NLC originating from the strong π-π interaction between benzene rings in the honeycomb-like graphene structure and in NLC molecules. The high-uniformity of reoriented GP flakes exhibits a possibility of new light modulation with a relatively faster response time in the switching process and, thus, it can show potential application in field-induced memory and modulation devices.

Coordination coupling enhanced two-photon absorption of a ZnS-based microhybrid for two-photon microscopy imaging in HepG2.

Coordination coupling induced self-assembly of ZnS microparticles was performed with the help of a π-conjugated sulphur-terminal Zn(ii) complex ZnS2L (L = N-hexyl-3-{2-[4-2,2':6',2''-terpyridin-4'-yl-phenyl]ethenyl}-carbazole). The interactions between ZnS and ZnS2L components at the interface, which were analyzed by far-IR and XPS, resulted in a tunable single-photon excited fluorescence and an enhanced nonlinear optical response, including a two-photon absorption cross section and a two-photon excited fluorescence. Such an enhancement in nonlinear optical properties was triggered by the coordination coupling effect between terminal S atoms of ZnS2L and naked Zn2+ ions at the surface of ZnS particles. Thus, the novel hybrid system displayed a unique two-photon excited fluorescence to facilitate promising two-photon microscopy imaging of HepG2 cells upon NIR light illumination at 840 nm. The hybrid shows a stronger ability to enter the cells than free ZnS2L.

Doping Zn(2+) in CuS Nanoflowers into Chemically Homogeneous Zn0.49Cu0.50S1.01 Superlattice Crystal Structure as High-Efficiency n-Type Photoelectric Semiconductors.

Doping Zn(2+) in CuS nanoflower into chemically homogeneous superlattice crystal structure is proposed to convert p-type CuS semiconductor to an n-type CuS semiconductor for significantly enhanced photoelectric response performance. In this study, the chemically homogeneous Zn-doped CuS nanoflowers (Zn0.06Cu0.94S, Zn0.26Cu0.73S1.01, Zn0.36Cu0.62S1.02, Zn0.49Cu0.50S1.01, Zn0.58Cu0.40S1.02) are synthesized by reacting appropriate amounts of CuCl and Zn(Ac)2·2H2O with sulfur powders in ethanol solvothermal process. By tuning the Zn/Cu atomic ratios to ∼1:1, the chemically homogeneous Zn-doped CuS nanoflowers could be converted to the perfect Zn0.49Cu0.50S1.01 superlattice structure, corresponding to the periodic Cu-S-Zn atom arrangements in the entire crystal lattice, which can induce an effective built-in electric field with n-type semiconductor characteristics to significantly improve the photoelectric response performance, such as the lifetime of photogenerated charge carriers up to 6 × 10(-8)-6 × 10(-4) s with the transient photovoltage (TPV) response intensity to ∼44 mV. This study reveals that the Zn(2+) doping in CuS nanoflowers is a key factor in determining the superlattice structure, semiconductor type, and the dynamic behaviors of charge carriers.

Nanoelectrical investigation and electrochemical performance of nickel-oxide/carbon sphere hybrids through interface manipulation.

Advanced hetero-nanostructured materials for electrochemical devices, such as Li-ion batteries (LiBs), dramatically depend on each functional component and their interfaces to transport and storage charges, where the bottleneck is the sluggish one in series. In this work, we prepare Ni(OH)2@C hybrids through a continuous feeding in reflux and followed by a hydrothermal treatment. The as-prepared Ni(OH)2@C can be further converted into NiO@C hybrids after thermal annealing. As a control, Ni(OH)2&C and NiO&C nanocomposites have also been prepared. Peakforce Tuna measurement shows the conductivity of the NiO@C hybrids is higher than that of NiO&C composites in nanoscale. To further investigate the quality of the interface, 100 charge/discharge cycles of the hybrids are performed in LiBs. The capacity retention of hybrid materials has significantly improved than the simple carbon composites. The enhancement of the electrochemical performance is attributed to the better electric conductivity and smaller charge transfer impedance and strong covalent interface between nickel species and carbon spheres obtained through the controlled seeded deposition.

Visible-Light Active and Magnetically Recyclable Nanocomposites for the Degradation of Organic Dye.

Recyclable visible-light photocatalyst Fe3O4@TiO2 with core-shell structure was prepared by a simple synthetic strategy using solvothermal crystallization of titanium precursor on preformed Fe3O4 nanopartiles. The photo-degradation reaction of neutral red aqueous solution was tested to evaluate the visible-light photocatalytic activity of the as prepared Fe3O4@TiO2 nanoparticles, which show excellent photocatalytic activity compared with commercial P25 catalyst. Moreover, the Fe3O4@TiO2 nanocomposites can be easily separated from the reaction mixture, and maintain favorable photocatalytic activity after five cycles. The high visible light absorption of the Fe3O4@TiO2 nanocomposites may originate from the absence of electronic heterojunction, excellently dispersity and the high specific surface area of the as-synthesized Fe3O4@TiO2 samples.

Photophysical properties of spherical aggregations of CdS nanocrystals capped with a chromophoric surface agent.

A novel sulfur-terminal Cd(II) complex, CdS(2)L (L = N-hexyl-3-{2-[4-(2,2':6',2''-terpyridin-4'-yl)phenyl]ethenyl}-carbazole), was successfully synthesized from CdS nanocrystals and the organic chromophores (L), which was confirmed by single-crystal X-ray diffraction analysis. Its photophysical properties have been investigated both experimentally and theoretically. The novel hybrid nanoparticles (CdS/L) were then obtained using the L as surface capped agent, which aggregate into large spheres, exhibiting novel luminescent properties, strong two photon absorption (TPA) and obvious prolonged fluorescence lifetime, which differ from those of the pure CdS nanocrystals and free L.

From nanoplates to microtubes and microrods: a surfactant-free rolling mechanism for facile fabrication and morphology evolution of Ag2S films.

By a simple and facile wet-chemistry technique without any surfactant, various shapes of Ag(2)S crystals--including leaflike pentagonal nanoplates, crinkly nanoscrolls, hexagonal prismlike microtubes, and microrods--were fabricated in situ on a large-area silver-foil surface separately. Detailed experiments revealed that the Ag(2)S nanoplates were formed just by immersing the silver foil in a sulfur/ethanol solution at room temperature and atmospheric pressure, and they subsequently rolled into nanoscrolls and further grew into microtubes and microrods under solvothermal conditions. Inspired by the natural curling of a piece of foliage, we proposed a surfactant-free rolling mechanism to interpret the observed morphological evolution from lamellar to tubular structures. Based on these simple, practical, and green chemical synthetic routes, we can easily synthesize lamellar, scrolled, tubular, and clubbed Ag(2)S crystals by simply adjusting the reaction temperature, pressure, and time. It is very interesting to note that the current rolling process is quite different from the previous reported rolling mechanism that highly depends on the surfactants; we revealed that the lamellar Ag(2)S could be rolled into tubular structures without using any surfactant or other chemical additives, just like the natural rolling process of a piece of foliage. Therefore, this morphology-controlled synthetic route of Ag(2)S crystals may provide new insight into the synthesis of metal sulfide semiconducting micro-/nanocrystals with desired morphologies for further industrial applications. The optical properties of the pentagonal Ag(2)S nanoplates/film were also investigated by UV/Vis and photoluminescence (PL) techniques, which showed large blue-shift of the corresponding UV/Vis and PL spectra.

A sulfur-terminal Zn(II) complex and its two-photon microscopy biological imaging application.

A novel sulfur-terminal Zn(II) complex Zn(S)(2)L (L = N-hexyl-3-{2-[4-(2,2':6',2''-terpyridin-4'-yl)phenyl] ethenyl}carbazole) was obtained by a facile solvothermal process. The unique feature in this new reaction design is the use of ZnS nanocrystals as a precursor and bulky chromophoric L as an ancillary ligand. The versatility of the two terminal sulfur atoms is relevant to biological system. The resulting Zn(S)(2)L complex shows two-photon excited fluorescence (TPEF), which has been proven to be potentially useful for two-photon microscopy imaging in living cells. In addition, cytotoxicity tests showed that the low-micromolar concentrations of Zn(S)(2)L did not cause significant reduction in cell viability over a period of at least 24 h and should be safe for further biological studies.