A Review on Microbial Electrocatalysis Systems Coupled with Membrane Bioreactor to Improve Wastewater Treatment

Microbial electrocatalysis is an electro reaction that uses microorganisms as a biocatalyst, mainly including microbial electrolytic cells (MEC) and microbial fuel cells (MFC), which has been used for wastewater treatment. However, the low processing efficiency is the main drawback for its practical application and the additional energy input of MEC system results in high costs. Recently, MFC/MEC coupled with other treatment processes, especially membrane bioreactors (MBR), has been used for high efficiency and low-cost wastewater treatment. In these systems, the wastewater treatment efficiency can be improved after two units are operated and the membrane fouling of MBR can also be alleviated by the electric energy that was generated in the MFC. In addition, the power output of MFC can also reduce the energy consumption of microbial electrocatalysis systems. This review summarizes the recent studies about microbial electrocatalysis systems coupled with MBR, describing the combination types and microorganism distribution, the advantages and limitations of the systems, and also addresses several suggestions for the future development and practical applications

Association Between Air Pollutants and Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Time Stratified Case-Crossover Design With a Distributed Lag Nonlinear Model

Acute exacerbation of chronic obstruction pulmonary disease (AECOPD) as a respiratory disease, is considered to be related to air pollution by more and more studies. However, the evidence on how air pollution affect the incidence of AECOPD and whether there are population differences is still insufficient. Therefore, we select PM10, PM2.5, SO2, NO2, CO, and O3 as representatives combined with daily AECOPD admission data from 1 January 2015 to 26 June 2016 in the rural areas of Qingyang, northwestern China to explore the associations of air pollution with AECOPD. Based on a time-stratified case-crossover design, we constructed a distributed lag nonlinear model to qualify the single and cumulative lagged effects of air pollution on AECOPD. Stratified related risks by sex and age were also reported. The cumulative exposure-response curves were approximately linear for PM2.5, “V”-shaped for PM10, “U”-shaped for NO2 and inverted-“V” for SO2, CO and O3. Exposure to high-PM2.5 (42 μg/m3), high-PM10 (91 μg/m3), high-SO2 (58 μg/m3), low-NO2 (12 μg/m3), and high-CO (1.55 mg/m3) increased the risk of AECOPD. Females aged 15–64 were more susceptible under extreme concentrations of PM2.5, SO2, CO, and low-PM10 than other subgroups. In addition, adults aged 15–64 were more sensitive to extreme concentrations of NO2 compared with the elderly ≥65 years old, while the latter were more sensitive to high-PM10. High-SO2, high-NO2, and extreme concentrations of PM2.5 had the greatest effects on the day of exposure, while low-SO2 and low-CO had lagged effects on AECOPD. Precautionary measures should be taken with a focus on vulnerable subgroups, to control hospitalization for AECOPD associated with air pollutants

Enhanced Thermal Conductivity of Phase Change Microcapsules Based on Boron Nitride/Graphene Oxide Composite Sheets

Large energy storage capacity and high heat conduction are very important for phase change materials. Phase change microcapsules (PCMCs) were synthesized through in situ polymerization by using paraffin as the core material. The melamine–formaldehyde (MF) polymer shell of PCMCs was modified with boron nitride/graphene oxide composite sheets (BN/GO CSs) to improve thermal conduction. The preparation condition of BN/GO CSs through the self-assembly process and the synthesis process of composite PCMCs (CPCMCs) in the presence of BN/GO CSs were systematically investigated. The thermal conductivity of CPCMCs synthesized under the optimized condition significantly increased about 190% relative to the incorporated paraffin. Promisingly, the introduction of BN/GO CSs hardly influenced the encapsulation process, allowing high encapsulation rate (>93%) and high phase change enthalpy (∼200 J·g–1). This work is an enlightening complementarity to the very limited research attempts that incorporating multiple fillers in PCMCs. We postulated and proved the synergistic effect of BN/GO CSs and their advantages in improving the thermal conductivity of the resultant PCMCs without scarifying the essential heat storage capacity. We envision that the insights and the CPCMCs synthesized can be applied in a range of material designs for energy and electronic applications

A Novel Early Warning System Based on a Sediment Microbial Fuel Cell for In Situ and Real Time Hexavalent Chromium Detection in Industrial Wastewater

Hexavalent chromium (Cr(VI)) is a well-known toxic heavy metal in industrial wastewater, but in situ and real time monitoring cannot be achieved by current methods used during industrial wastewater treatment processes. In this study, a Sediment Microbial Fuel Cell (SMFC) was used as a biosensor for in situ real-time monitoring of Cr(VI), which was the organic substrate is oxidized in the anode and Cr(VI) is reduced at the cathode simultaneously. The pH 6.4 and temperature 25 °C were optimal conditions for the operation. Under the optimal conditions, linearity (R2 = 0.9935) of the generated voltage was observed in the Cr(VI) concentration range from 0.2 to 0.7 mg/L. The system showed high specificity for Cr(VI), as other co-existing ions such as Cu2+, Zn2+, and Pb2+ did not interfere with Cr(VI) detection. In addition, when the sediment MFC-based biosensor was applied for measuring Cr(VI) in actual wastewater samples, a low deviation (<8%) was obtained, which indicated its potential as a reliable biosensor device. MiSeq sequencing results showed that electrochemically active bacteria (Geobacter and Pseudomonas) were enriched at least two-fold on the biofilm of the anode in the biosensor as compared to the SMFC without Cr(VI). Cyclic voltammetry curves indicated that a pair of oxidation/reduction peaks appeared at −111 mV and 581 mV, respectively. These results demonstrated that the proposed sediment microbial fuel cell-based biosensor can be applied as an early warning device for real time in situ detection of Cr(VI) in industrial wastewaters

Structural and functional insights into a novel two-component endolysin encoded by a single gene in Enterococcus faecalis phage.

Using bacteriophage-derived endolysins as an alternative strategy for fighting drug-resistant bacteria has recently been garnering renewed interest. However, their application is still hindered by their narrow spectra of activity. In our previous work, we demonstrated that the endolysin LysIME-EF1 possesses efficient bactericidal activity against multiple strains of Enterococcus faecalis (E. faecalis). Herein, we observed an 8 kDa fragment and hypothesized that it contributes to LysIME-EF1 lytic activity. To examine our hypothesis, we determined the structure of LysIME-EF1 at 1.75 Å resolution. LysIME-EF1 exhibits a unique architecture in which one full-length LysIME-EF1 forms a tetramer with three additional C-terminal cell-wall binding domains (CBDs) that correspond to the abovementioned 8 kDa fragment. Furthermore, we identified an internal ribosomal binding site (RBS) and alternative start codon within LysIME-EF1 gene, which are demonstrated to be responsible for the translation of the truncated CBD. To elucidate the molecular mechanism for the lytic activity of LysIME-EF1, we combined mutagenesis, lytic activity assays and in vivo animal infection experiments. The results confirmed that the additional LysIME-EF1 CBDs are important for LysIME-EF1 architecture and its lytic activity. To our knowledge, this is the first determined structure of multimeric endolysin encoded by a single gene in E. faecalis phages. As such, it may provide valuable insights into designing potent endolysins against the opportunistic pathogen E. faecalis

RNA-Seq Provides Insights into the Mechanisms Underlying Ilyonectria robusta Responding to Secondary Metabolites of Bacillus methylotrophicus NJ13

(1) Background: Ilyonectria robusta can cause ginseng to suffer from rusty root rot. Secondary metabolites (SMs) produced by Bacillus methylotrophicus NJ13 can inhibit the mycelial growth of I. robusta. However, the molecular mechanism of the inhibition and response remains unclear. (2) Methods: Through an in vitro trial, the effect of B. methylotrophicus NJ13’s SMs on the hyphae and conidia of I. robusta was determined. The change in the physiological function of I. robusta was evaluated in response to NJ13’s SMs by measuring the electrical conductivity, malondialdehyde (MDA) content, and glucose content. The molecular interaction mechanism of I. robusta’s response to NJ13’s SMs was analyzed by using transcriptome sequencing. (3) Results: NJ13’s SMs exhibited antifungal activity against I. robusta: namely, the hyphae swelled and branched abnormally, and their inclusions leaked out due to changes in the cell membrane permeability and the peroxidation level; the EC50 value was 1.21% (v/v). In transcripts at 4 dpi and 7 dpi, the number of differentially expressed genes (DEGs) (|log2(fold change)| > 1, p adj ≤ 0.05) was 1960 and 354, respectively. NJ13’s SMs affected the glucose metabolism pathway, and the sugar-transporter-related genes were downregulated, which are utilized by I. robusta for energy production. The cell wall structure of I. robusta was disrupted, and chitin-synthase-related genes were downregulated. (4) Conclusions: A new dataset of functional responses of the ginseng pathogenic fungus I. robusta was obtained. The results will benefit the development of targeted biological fungicides for I. robusta and the study of the molecular mechanisms of interaction between biocontrol bacteria and phytopathogenic fungi

A Review on Nanoparticles as Boon for Biogas Producers—Nano Fuels and Biosensing Monitoring

Nanotechnology has an increasingly large impact on a broad scope of biotechnological, pharmacological and pure technological applications. Its current use in bioenergy production from biomass is very restricted. The present study is based on the utilization of nanoparticles as an additive to feed bacteria that break down natural substances. The novel notion of dosing ions using modified nanoparticles can be used to progress up biogas production in oxygen free digestion processes. While minute nanoparticles are unstable, they can be designed to provide ions in a controlled approach, so that the maximum enhancement of biogas production that has been reported can be obtained. Nanoparticles are dissolved in a programmed way in an anaerobic atmosphere and are supplied in a sustainable manner to microbiotic organisms responsible for the degradation of organic material, which is a role that fits them well. Therefore, biogas fabrication can be increased up to 200%, thereby increasing the degradation of organic waste

Functional studies of split Arabidopsis Ca2+/H+ exchangers

In plants, high capacity tonoplast cation/H(+) antiport is mediated in part by a family of cation exchanger (CAX) transporters. Functional association between CAX1 and CAX3 has previously been shown. In this study we further examine the interactions between CAX protein domains through the use of nonfunctional halves of CAX transporters. We demonstrate that a protein coding for an N-terminal half of an activated variant of CAX1 (sCAX1) can associate with the C-terminal half of either CAX1 or CAX3 to form a functional transporter that may exhibit unique transport properties. Using yeast split ubiquitin, in planta bimolecular fluorescence complementation, and gel shift experiments, we demonstrate a physical interaction among the half proteins. Moreover, the half-proteins both independently localized to the same yeast endomembrane. Co-expressing variants of N- and C-terminal halves of CAX1 and CAX3 in yeast suggested that the N-terminal region mediates Ca(2+) transport, whereas the C-terminal half defines salt tolerance phenotypes. Furthermore, in yeast assays, auto-inhibited CAX1 could be differentially activated by CAX split proteins. The N-terminal half of CAX1 when co-expressed with CAX1 activated Ca(2+) transport, whereas co-expressing C-terminal halves of CAX variants with CAX1 conferred salt tolerance but no apparent Ca(2+) transport. These findings demonstrate plasticity through hetero-CAX complex formation as well as a novel means to engineer CAX transport

Mapping formation mechanisms and transformation regimes of multiple Fe precipitates in Cu-Fe-Co alloy during casting process

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