Alcohol solvent effect on the self-assembly behaviors of lignin oligomers

The interactions between lignin oligomers and solvents determine the behaviors of lignin oligomers self-assembling into uniform lignin nanoparticles(LNPs).Herein,several alcohol solvents,which readily interact with the lignin oligomers,were adopted to study their effects during solvent shifting process for LNPs’production.The lignin oligomers with widely distributed molecular weight and abundant guaiacyl units were extracted from wood waste(mainly consists of pine wood),exerting outstanding self-assembly capability.Uniform and spherical LNPs were generated in H_(2)O-n-propanol cosolvent,whereas irregular LNPs were obtained in H_(2)O-methanol cosolvent.The unsatisfactory self-assembly performance of the lignin oligomers in H_(2)O-methanol cosolvent could be attributed to two aspects.On one hand,for the initial dissolution state,the distinguishing Hansen solubility parameter and polarity between methanol solvent and lignin oligomers resulted in the poor dispersion of the lignin oligomers.On the other hand,strong hydrogen bonds between methanol solvent and lignin oligomers during solvent shifting process,hindered the interactions among the lignin oligomers for self-assembly.

Antioxidant,antimicrobial,and α-glucosidase inhibitory activities of saponin extracts from walnut(Juglans regia L.) leaves

Objective:To investigate the relationship between triterpenoid saponin content and antioxidant,antimicrobial,and α-glucosidase inhibitory activities of 70%ethanolic,butanolic,aqueous,supernate and precipitate extracts of Juglans regia leaves.Methods:Triterpenoid saponins of different Juglans regia leaf extracts were measured by the vanillin method.Antioxidant activity was evaluated against DPPH and ABTS free radicals.We also assessed α-glucosidase inhibitory and antimicrobial activities of the leaf extracts.Pearson’s correlation coefficient was evaluated to determine the correlation between the saponin content and biological activities.Results:The butanolic extract was most effective against DPPH with an IC50of 6.63μg/mL,while the aqueous extract showed the highest scavenging activity against ABTS free radical with an IC50of 42.27μg/mL.Pearson’s correlation analysis indicated a strong negative correlation (r=-0.956) between DPPH radical scavenging activity (IC50) and the saponin content in the samples examined.In addition,the aqueous extract showed the best α-glucosidase inhibitory activity compared with other extracts.All the extracts had fair antibacterial activity against Bacillus subtilis,Escherichia coli,and Klebsiella pneumoniae except for the aqueous extract.Conclusions:Juglans regia extracts show potent antioxidant,antimicrobial,and α-glucosidase inhibitory activities.There is a correlation between saponin levels in Juglans regia leaf extracts and the studied activities.However,additional research is required to establish these relationships by identifying the specific saponin molecules responsible for these activities and elucidating their mechanisms of action.

流动电极微生物电合成提高产物生成速率及降低能量消耗

微生物电合成(microbial electrosynthesis,MES)利用可再生电力驱动微生物固定CO_(2)合成化学品,在推进碳循环经济中具有一定潜力,受到广泛关注。但是,很少有研究通过高效反应器设计来促进产乙酸并降低能耗。本研究中,新型流动电极MES反应器的总产乙酸速率[(16±1)g·m^(-2)·d^(-1)]比无粉末活性炭(powder activated carbon,PAC)对照[(8±3)g·m^(-2)·d^(-1)]高两倍。流动电极MES反应器的库伦效率为43.5%±3.1%,能量消耗为(0.020±0.005)k Wh·g^(-1),产乙酸的能量效率为18.7%±1.3%。基于PAC的流动电极能够降低水跨膜通量、传质阻力,但是对装置电压、流变行为、乙酸吸附的影响较小。流动电极MES反应器中,能量代谢相关基因高表达,Acetobacterium的丰度增加。MES反应器中同时存在用于碳固定的还原性乙酰辅酶A途径(Wood–Ljungdahl pathway,WLP)与还原性三羧酸循环途径(reductive citric acid cycle,r TCA)。堆叠型流动电极MES中的乙酸浓度达7.0 g·L^(-1)。本研究提供一种构建可扩展MES反应器的新方法,促进CO_(2)利用以及产物生成。

A novel and complete gene cluster involved in the degradation of aniline by Delftia sp. AN3

A recombinant strain, Escherichia coli JM109-AN1, was obtained by constructing of a genomic library of the total DNA of Delftia sp. AN3 in E. coli JM109 and screening for catechol 2,3-dioxygenase activity. This recombinant strain could grow on aniline as sole carbon, nitrogen and energy source. Enzymatic assays revealed that the exogenous genes including aniline dioxygenase （AD） and catechol 2,3-dioxygenase （C230） genes could well express in the recombinant strain with the activities of AD and C230 up to 0.31 U/mg wet cell and 1.92 U/mg crude proteins, respectively. The AD or C23O of strain AN3 could only catalyze aniline or catechol but not any other substituted substrates. This recombinant strain contained a recombinant plasmid, pKC505-AN1, in which a 29.7-kb DNA fragment from Delftia sp. AN3 was inserted. Sequencing and open reading frame （orfs） analysis of this 29.7 kb fragment revealed that it contained at least 27 orfs, among them a gene cluster （consisting of at least 16 genes, named danQTA1A2BRDCEFG1HIJKG2） was responsible for the complete metabolism of aniline to TCA-cycle intermediates. This gene cluster could be divided into two main parts, the upper sequences consisted of 7 genes （danQTA1A2BRD） were predicted to encode a multi-component aniline dioxygenase and a LysR-type regulator, and the central genes （danCEFG1HIJKG2） were expected to encode meta-cleavage pathway enzymes for catechol degradation to TCA-cycle intermediates. Unlike clusters tad from Delftia tsuruhatensis AD9 and tdn from Pseudomonas putida UCC22, in this gene cluster, all the genes were in the same transcriptional direction. There was only one set of C230 gene （danC） and ferredoxin-like protein gene （danD）. The presence of only one set of these two genes and specificity of AD and C230 might be the reason for strain AN3 could only degrade aniline. The products of danQTA1A2BRDC showed 99%-100% identity to those from Delftia acidovorans 7N, and 50%-85% identity to those of tad cluster from D. tsuruhatensis AD9 in amino acid residues. Besides this dan cluster, the 29.7 kb fragment also contained genes encoding the trans-membrane transporter and transposases which might be needed for transposition of the gene cluster. Pulsed-field gel electrophoresis （PFGE） and plasmid curing experiments suggested that the dan cluster might be encoded on the chromosome of strain AN3. The GenBank accession number for the dan cluster of Delftia sp. AN3 is DQ661649.

Effect of organic carbon on nitrification effciency and community composition of nitrifying biofilms

The effects of organic carbon/inorganic nitrogen （C/N） ratio on the nitrification processes and the community shifts of nitrifying biofilms were investigated by kinetic comparison and denaturing gradient gel electrophoresis （DGGE） analysis. The results showed that the nitrification rate decreased with an increasing organic concentration. However, the effect became weak when the carbon concentration reached a sufficiently high level. Denitrification was detected after organic carbon was added. The 12 h ammonium removal rate ranged from 85% to 30% at C/N = 0.5, 1, 2, 4, 8, and 16, as compared to the control （C/N = 0）. The loss of nitrogen after 24 h at C/N = 0.5, 1, 2, 4, 8, and 16 was 31%, 18%, 24%, 65%, 59%, and 62%, respectively. The sequence analysis of 16S rRNA gene fragments revealed that the dominant populations changed from nitrifying bacteria （Nitrosomonas europaea and Nitrobacter sp.） to denitrifying bacteria （Pseudomonas sp., Acidovorax sp. and Comamonas sp.） with an increasing C/N ratio. Although at high C/N ratio the denitrifying bacteria were the dominant populations, nitrifying bacteria grew simultaneously. Consequently, nitrification process coexisted with denitrification.

Recent advances in detoxification strategies for zearalenone contamination in food and feed

Zearalenone(ZEN)is a widely distributed mycotoxin that frequently contaminates crops and animal feed.ZEN can cause serious health problems in livestock and humans alike,leading to great economic losses in the food industry and livestock farming.Therefore,approaches for efficient ZEN decontamination in food and feed are urgently needed.Traditional physical and chemical methods may decrease the nutritional quality of food and palatability of feed,or leading to residues and safety concerns.By contrast,biological methods for the removal or degradation of ZEN overcome these problems,especially for biological degradation by microorganisms and specific enzymes extracted from strains that can convert ZEN to less toxic or even completely harmless products.In this review,we comprehensively describe methods for ZEN degradation,focusing especially on biological strategies.Finally,emerging strategies and advice on remaining challenges in biodegradation research are also briefly discussed.

Inhibition of Japanese Encephalitis Virus Infection by Flavivirus Recombinant E Protein Domain Ⅲ

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus closely related to the human pathogens including yellow fever virus, dengue virus and West Nile virus. There are currently no effective antiviral therapies for all of the flavivirus and only a few highly effective vaccines are licensed for human use. In this paper, the E protein domain III (DIII) of six heterologous flaviviruses (DENV1-4, WNV and JEV) was expressed in Escherichia coli successfully. The proteins were purified after a solubilization and refolding procedure, characterized by SDS-PAGE and Western blotting. Competitive inhibition showed that all recombinant flavivirus DIII proteins blocked the entry of JEV into BHK-21 cells. Further studies indicated that antibodies induced by the soluble recombinant flavivirus DIII partially protected mice against lethal JEV challenge. These results demonstrated that recombinant flavivirus DIII proteins could inhibit JEV infection competitively, and immunization with proper folding flavivirus DIII induced cross-protection against JEV infection in mice, implying a possible role of DIII for the cross-protection among flavivirus as well as its use in antigens for immunization in animal models.

Surface Display of Domain Ⅲ of Japanese Encephalitis Virus E Protein on Salmonella Typhimurium by Using an Ice Nucleation Protein

A bacterial cell surface display technique based on an ice nucleation protein has been employed for the development of live vaccine against viral infection. Due to its ubiquitous ability to invade host cells, Salmonella typhimurium might be a good candidate for displaying viral antigens. We demonstrated the surface display of domain III of Japanese encephalitis virus E protein and the enhanced green fluorescent protein on S. typhimurium BRD509 using the ice nucleation protein. The effects of the motif in the ice nucleation protein on the effective display of integral protein were also investigated. The results showed that display motifs in the protein can target integral foreign protein on the surface of S. typhimurium BRD509. Moreover, recombinant strains with surface displayed viral proteins retained their invasiveness, suggesting that the recombinant S. typhimurium can be used as live vaccine vector for eliciting complete immunogenicity. The data may yield better understanding of the mechanism by which ice nucleation protein displays foreign proteins in the Salmonella strain.

Characterization of Aquabacterium parvum sp. Strain B6 during Nitrate-Dependent Fe(Ⅱ) Oxidation Batch Cultivation with Various Impact Factors

In order to assess the capacity of Aquabacterium parvum sp. strain B6 for nitrate-dependent Fe(II) oxidation, batch cultivation was conducted, and its ability to oxidize Fe(II) coupled to nitrate reduction in the presence of diverse organic substrates was studied. Meanwhile, the nitrate-removal rate of B6 with various impact factors was further optimized by the response surface methodology (RSM). The results show that strain B6 is capable of utilizing different organic compounds as substrates for nitrate reduction. Compared with yeast extract, B6 showed a greater potential of chemical oxygen demand (COD) degradation and cell proliferation with acetate and glucose mediums, respectively, while citrate was not beneficial for this process due to its low consumption rate. RSM analysis demonstrated that the maximum nitrate-reduction rate of 30.64% could be achieved with an initial pH of 7.4, incubation temperature of 25.0 °C, and carbon source concentration of 266.10 mg/L. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

Molecular Characterization of China Human Rabies Vaccine Strains

To understand the molecular characteristics of China human rabies vaccine strains, we report the full-length genome of the aG strain and present a comprehensive analysis of this strain and almost all available lyssavirus genomes （58 strains） from GenBank （as of Jan 6, 2011）. It is generally considered that the G protein plays a predominant role in determining the pathogenicity of the virus, to this end we predicted the tertiary structure of the G protein of aG strain, CTN 181 strain and wild type strain HN 10 based on the crystal structure of Vesicular stomatitis virus （VSV） G. The predicted RABV G structure has a similar topology to VSV G and the ectodomain can be divided into 4 distinct domains DI - DIV. By mapping the characterized mutations to this structure between China vaccine strains and their close street strains, we speculate that the G303（P-H） mutations of CTN181 and HN10 causing D II 3D change may be associated with the attenuated virulence in both strains. Specifically, the two signature mutations （G165P and G231P） in the aG strain are withinβsheets, suggesting that both sites are of structural importance.

Mutagenesis of D80-82 and G83 Residues in West Nile Virus NS2B: Effects on NS2B-NS3 Activity and Viral Replication

Flaviviral NS2B is a required cofactor for NS3 serine protease activity and plays an important role in promoting functional NS2B-NS3 protease configuration and maintaining critical interactions with protease catalysis substrates. The residues D80DDG in West Nile virus (WNV) NS2B are important for protease activity. To investigate the effects of D80DDG in NS2B on protease activity and viral replication, the negatively charged region D80DD and the conserved residue G83 of NS2B were mutated (D80DD/E80EE, D80DD/K80KK, D80DD/A80AA, G83F, G83S, G83D, G83K, and G83A), and NS3 D75A was designated as the negative control. The effects of the mutations on NS2B-NS3 activity, viral translation, and viral RNA replication were analyzed using kinetic analysis of site-directed enzymes and a transient replicon assay. All substitutions resulted in significantly decreased enzyme activity and blocked RNA replication. The negative charge of D80DD is not important for maintaining NS2B function, but side chain changes in G83 have dramatic effects on protease activity and RNA replication. These results demonstrate that NS2B is important for viral replication and that D80DD and G83 substitutions prevent replication; they will be useful for understanding the relationship between NS2B and NS3.

Semen analysis in chronic bacterial prostatitis： diagnostic and therapeutic implications

The significance and diagnostic value of semen analysis in chronic bacterial prostatitis has been extensively debated and remains controversial. To investigate the diagnostic relevance of semen culture in the bacteriological workup of prostatitis patients, we retrospectively analyzed a clinical database of 696 symptomatic patients. All patients were routinely subjected to a four-glass test, followed by semen culture and analysis. This allowed to dissect from the database three different diagnostic scenarios, and to compare the ＇two-glass＇ pre-/post- massage test and the standard ＇four-glass＇ test with a ＇five-glass＇ test （four-glass plus post-VB3 semen culture）. The ＇five-glass＇ test showed 3.6- or 6.5-fold increases in relative sensitivity and lesser reductions （-13.2% or -14.7%） in relative specificity for traditional uropathogens （TUs） compared with the four-glass or two-glass test, respectively. The area under the ROC curve and Jouden＇s index were increased, whereas positive and negative likelihood ratios were lower than comparators, indicating that the ＇five-glass＇ assay may be superior in confirming the negative outcome of both standard tests. The five-, four-, and two-glass tests detected TUs （Enterobacteriaceae, Enterococci, etc.） in 120, 33, and 20 patients and unusual pathogens （Streptococci, other Gram-positive species, Mycoplasmata, and others） in 130, 56, and 45 patients, respectively. When patients were subjected to pharmacological treatment, including a combination of a fluoroquinolone and a macrolide, no differences in eradication rates were observed between groups diagnosed with different tests, irrespective of pathogen category. Eradication was associated with long-term sign/symptom remission; no significant intergroup differences in sign/symptom scores were observed throughout a 24-month off-therapy follow-up period. In conclusion, our data support the usefulness of semen analysis in the diagnostic workup ofprostatitis patients when this test is used to complement the four-glass Meares and Stamey test. Improvement of microbiological assays conveys important diagnostic and therapeutic implications.

Critical role of Dengue Virus NS1 protein in viral replication

Dengue virus(DENV) nonstructural protein 1(NS1) is a highly conserved 46-kDa protein that contains 2 glycosylation sites(Asn-130 and Asn-207) and 12 conserved cysteine(Cys) residues. Here, we performed site-directed mutagenesis to generate systematic mutants of viral strain TSV01. The results of the subsequent analysis showed that an alanine substitution at the second N-linked glycan Asn-207 in NS1 delayed viral RNA synthesis, reduced virus plaque size, and weakened the cytopathic effect. Three mutants at Cys sites(Cys-4, Cys-55, Cys-291) and a C-terminal deletion(ΔC) mutant significantly impaired RNA synthesis, and consequently abolished viral growth, whereas alanine mutations at Asn-130 and Glu-173 resulted in phenotypes that were similar to the wild-type(WT) virus. Further analysis showed that the Asn-207 mutation slightly delayed viral replication. These results suggest that the three conserved disulfide bonds and the second N-linked glycan in NS1 are required for DENV-2 replication.

First report of a new potato disease caused by Galactomyces candidum F12 in China

Potato(Solanum tuberosum L.)is an important crop throughout the world.An uncharacterized disease has been observed on potato plants during the growing season and tubers during the storage period from Nileke County,Qitai County and other locations in Xinjiang,China.A particular fungus was consistently isolated from the infected potato plants and tubers.Based on its morphology,molecular characteristics,pathogenicity test and internal transcribed spacer(ITS)sequence,the pathogens was identified as Galactomyces candidum F12.Further study also showed that the hyphae and conidia of the pathogenic fungus grew faster as the temperature was 30℃,pH was 7,soluble starch was used as optimal carbon source and yeast powder as optimal nitrogen source.In addition,12-h continuous ilumination light was beneficial to the hyphal growth,while 24-h continuous ilumination was beneficial to the sporulation of the strain at 30℃.To our knowledge,this is the first report of Galactomyces candidum causing leaf wilt and postharvest tuber rot on potato in China.

Investigation of the Evolutionary History of the Lyssaviruses

Dear Editor, We report the results of evolutionary history estimation of the lyssaviruses based on an analysis of the Glycoprotein (G) sequences gene using the BEAST software package. The most recent common ancestor (TMRCA) of all the lyssavirus strains was estimated to be approximately 5030 years (95% HPD 3988-6069 years), and there was a significant spread of the rabies virus throughout the world range in the last 200 years, consistent with significant time points in development and migration of human civilizations.

Development and Characterization of West Nile Virus Replicon Expressing Secreted Gaussia Luciferase

We developed a Gaussia luciferase (Gluc) reporter replicon of West Nile virus (WNV) and used it to quantify viral translation and RNA replication. The advantage of the Gluc replicon is that Gaussia luciferase is secreted into the culture medium from cells transfected with Gluc replicon RNA, and the medium can be assayed directly for luciferase activity. Using a known Flavivirus inhibitor (NITD008), we demonstrated that the Gluc-WNV replicon could be used for antiviral screening. The Gluc-WNV-Rep will be useful for research in antiviral drug development programs, as well as for studying viral replication and pathogenesis of WNV.

Interplay of S and As in Mekong Delta sediments during redox oscillations

The cumulative effects of periodic redox cycling on the mobility of As,Fe,and S from alluvial sediment to groundwater were investigated in bioreactor experiments.Two particular sediments from the alluvial floodplain of the Mekong Delta River were investigated: Matrix A (14 m deep) had a higher pyrite concentration than matrix B (7 m deep) sediments.Gypsumwas present in matrix B but absent in matrix A.In the reactors,the sediment suspensions were supplemented with As(III) and SO4^2-,and were subjected to three full-redox cycles entailing phases of nitrogen/CO2,compressed air sparging,and cellobiose addition.Major differences in As concentration and speciation were observed upon redox cycling.Evidences support the fact that initial sediment composition is the main factor controlling arsenic release and its speciation during the redox cycles.Indeed,a high pyrite content associated with a low SO4^2- content resulted in an increase in dissolved As concentrations,mainly in the form of As(III),after anoxic half-cycles;whereas a decrease in As concentrations mainly in the form of As(V),was instead observed after oxic half-cycles.In addition,oxic conditions were found to be responsible for pyrite and arsenian pyrite oxidation,increasing the As pool available for mobilization.The same processes seem to occur in sediment with the presence of gypsum,but,in this case,dissolved As were sequestered by biotic or abiotic redox reactions occurring in the FeeS system,and by specific physico-chemical condition (e.g.pH).The contrasting results obtained for two sediments sampled from the same core show that many complexes and entangled factors are at work,and further refinement is needed to explain the spatial and temporal variability of As release to groundwater of the Mekong River Delta (Vietnam).

Antibiogram of Escherichia coli and Pseudomonas Strains Isolated from Wastewater Generated by an Abattoir as It Journeys into a Receiving River

Untreated wastewater from abattoir operations contains nutrients and other components that aid the growth of microorganisms especially bacteria. They also serve as a habitat for potentially pathogenic bacteria which might be a source of public health concern. The study was carried out to determine the antibiotics susceptibility profile of Gram-negative bacteria (Pseudomonas and Escherichia coli) to selected antibiotics. Wastewater samples were collected from ten different sampling points and cultured on Eosin Methylene Blue (EMB) and King’s B medium. The bacterial strains obtained from the wastewater samples were subjected to antibiotics susceptibility tests, using the disc diffusion technique. A total of 60 Pseudomonas and 100 Escherichia coli were isolated out of which none of the Pseudomonas strains showed resistance to imipenem, colistin sulphate, meropenem and aztreonam, while 100% resistance was observed to ceftazidime and piperacillin. All the Escherichia coli strains were resistant to oxacillin and ceftazidime, while the percentage resistance to aztreonam, ertapenem, cefoxitin and tetracyline was 6%, 11%, 43% and 58% respectively. Eighty-five percent (85%) of the total Escherichia coli showed resistance to more than two antibiotics, while 14% showed resistance to ceftazidime and oxacillin, with only one isolate showing resistance to ceftazidime and cefoxitin. There is the need for an effective treatment of wastewater generated from abattoir operations to prevent the potential spread and transmission of antibiotic resistant bacteria to the human population who depends heavily on some of the water bodies, receiving input from abattoir wastes.

The limited number of available nucleotide and protein sequence data from the recent H7N9 cases in China impeded investigation and characterization of the outbreak

Dear Editor,Nucleotide and protein sequences of isolates collectedfrom infected populations can be useful for determiningthe threats,such as host adaptation,which are associatedwith the emergence of new lineages.March 2013 saw thefirst reports of a new H7N9 lineage in Shanghai,Chinathat saw a gradual increase in the number of cases;but,by 17th May 2013,four Chinese provinces had

In vitro assessment of the synergism between extracts of Cocos nucifera husk and some standard antibiotics

Objective: To evaluate the interactions between the crude extracts of Cocos nucifera(C.nucifera) and six front line antibiotics(ampicillin sodium salt, penicillin G sodium,amoxicillin, chloramphenicol, ciprofloxacin and tetracycline hydrochloride), against some bacterial pathogens linked with human infection.Methods: The pulverized husk of C.nucifera was dissolved in 95% n-hexane and extracted using Soxhlet extraction method and sterile distilled water(aqueous).The antibacterial susceptibility of the crude extracts of C.nucifera was tested against environmental and clinical strains(6) obtained from the South African Bureau of Standards(SABS), Vibrio(6) and Listeria pathogens(6).The agar-well diffusion method was used for screening the extracts for their antibacterial activity.The minimum inhibitory concentration and minimum bactericidal concentration of the extracts were determined.Time-kill assay was used to evaluate bactericidal and/or bacteriostatic activity.The synergistic effect of the crude extracts and antibiotics was assessed and evaluated by adopting the checkerboard methods.Results: With the time-kill assay, the highest bactericidal activity was observed on Vibrio fluvialis EL041 with a-5.6 ± 0.2 log_(10)CFU/mL decrease in cell density as a result of the combination of the extracts and chloramphenicol at two-fold minimum inhibitory concentrations.Synergisms using the time-kill assay constituted about 72%, while indifference constituted about 28%.The checkerboard method revealed synergistic interaction in 67% of the combinations, and indifference in 33%.There was no specificity in the observed synergy to a particular class of antibiotics.Conclusions: This investigation suggests the crude extracts of C.nucifera to be a potential broad spectrum antimicrobial compound.Therefore, further study is needed to isolate the pure compounds from these crude extracts.