Molecular Characterization and Antibacterial Activity of a G-Type Lysozyme in Yellow Drum(Nibea albiflora)

Lysozyme(EC3.2.1.17)plays an important role in the immune response;as a nonspecific immune factor,it can resist causative agents.Lysozyme can be divided into c-type and g-type in fish.In a previous study,through genome-wide association analysis,the g-type lysozyme gene,which is named NaLyg in yellow drum(Nibea albiflora),was found to be a key candidate gene for disease resistance in response to Vibrio harveyi infection.The cDNA of NaLyg was 1025 bp,including four exons and three introns,and its open reading frame(ORF)had a full-length of 582 bp,encoding 193 amino acids.NaLyg was found to be conserved during evolution through bioinformatic analyses.The NaLyg protein possessed a sugar binding domain and three catalytic sites,including Glu71,Asp84 and Asp101.Quantitative qRT-PCR results confirmed that NaLyg gene mRNA was visibly increased after V.harveyi infection.The NaLyg protein purified by prokaryotic expression killed some gram-negative bacterial pathogens by inducing cell wall destruction,including V.harveyi,Aeromonas hydrophila and Edwardsiella tarda.Moreover,the NaLyg protein killed two gram-positive bacteria,Bacillus subtilis and Staphylococcus aureus.Taken together,the experimental results suggested that the NaLyg protein of N.albiflora played an important role in fighting bacterial infections.

Synthesis and Excellent Antibacterial Activity of Ag_(2)O-Loaded Carboxymethyl Starch Nanocomposites

Carboxymethyl starch/silver oxide nanocomposites(CMS-Ag_(2)O NCs)were successfully fabricated by modifying carboxymethyl starch(CMS)with Ag_(2)O obtained from an aqueous AgNO_(3)solution as silver source.Ag_(2)O nanoparticles(NPs)formed on the surface of CMS by ion exchange.Based on SEM images,the diameters of Ag_(2)O NPs were determined to be between 50 and 100 nm.From the XRD spectra of CMS-Ag_(2)O NCs,the new diffraction peaks appeared at 33.88°and 38.08°,which were attributed to the Ag_(2)O NPs.According to the XPS analysis,Ag 3d_(5/2)and Ag 3d_(3/2)peaks in CMS-Ag_(2)O NCs were fitted into two main peaks centered at 367.6 eV and 373.6 eV,which were attributed to Ag^(+).The antibacterial efficiencies of CMS-Ag_(2)O NCs against Escherichia coli,Staphylococcus aureus,Pseudoalteromonas tetraodonis,Micrococcus luteus,and Shewanella putrefaciens were determined to be 99.6%,99.7%,99.4%,99.5%,and 99.6%,respectively.The antibacterial efficiencies of CMS-Ag_(2)O NCs against the bacterial species were all greater than 99%.Therefore,these results indicated that CMS-Ag_(2)O NCs was highly effective as a bactericidal agent against multiple bacterial species.CMS-Ag_(2)O NCs can be further applied to antifouling coating.

Review on Zinc Oxide Nanoparticles: Antibacterial Activity and Toxicity Mechanism

Antibacterial activity of zinc oxide nanoparticles(Zn O-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. Zn O-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. Zn O is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered Zn O-NPs antibacterial activity including testing methods, impact of UV illumination, Zn O particle properties(size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species(ROS) including hydrogen peroxide(H2O2), OH-(hydroxyl radicals), and O2-2(peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to Zn O-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions.These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on Zn O abrasive surface texture. One functional application of the Zn O antibacterial bioactivity was discussed in food packaging industry where Zn O-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of Zn O-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.

Expression of Recombinant Human Lysozyme-tachyplesin I(hLYZ-TP I)in Pichia Pastoris and Analysis of Antibacterial Activity

Antimicrobial peptides （AMPs） are making headlines in science because they demonstrate superior microbicidal characteristics compared to synthetic and semi-synthetic antibiotics.

Structure and antibacterial activity of Ce3+ exchanged montmorillonites

Four kinds of Ce3+ exchanged montmorillonites (Ce/MMTs) were prepared by an ion-exchange reaction, and characterized with energy dispersive X-ray analysis (EDX), X-ray difference (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The surface properties and antibacterial activity of Ce/MMTs were also investigated. The chemical compositions of Ce/MMTs were determined, and the cerium of Ce/MMTs was confirmed to be present as trivalent cerium state. The d001 basal spacings of Ce/MMTs were enlarged with the enhancement of the cerium contents, and the particles were formed with irregular shape. On increasing the Ce contents of Ce/MMTs, the special surface areas were decreased, but the total pore volumes and the average pore sizes were increased. The antibacterial activity of Ce/MMTs is increased with increasing the cerium contents, and 1.5 g/L of Ce/MMT-3 containing 11.46wt.% of curium could remove all the Staphylococcus aureus and more than 99.9% of the Escherichia coli within 24.0 h of contact. Moreover, Ce/MMTs displayed bactericidal activity.

Studies on the Antibacterial Activity of the Extract of Stachytarpheta angusti folia

To investigate the scientific bases for t/te traditional use of Stachy-tarpheta angustifolia. Methods: In vitro antibacterial activity of the aqueous and ethanol extract of the plant was investigated using the agar cup plate diffusion method. Results: The ethanol extract of the plant showed antibacterial activity against Escherichia coli, Streptococcus faecalis, Shigella dysenterme, Slaphylococcus aureus (S. aureus) , Salmonella sp. , Pseudomonas aeruginosa and Neisseria gonor-r/iaeae, while the water extract was active against Escherichia coli, Streptococcus faecalis, Shigella dysenterme, Sta-phylococcus aureus and. Pseudomonas aeruginosa. The etlianol extract exhibited higher antibacterial activity than the water extract. The minimum inhibitory concentration (MIC) and minimum bactericidal, concentration (MBC} of the ethanol extract were 0. 65 mg/mt and 0. 85 mg/ml, respectively , against S. aureus. Treatment of the extract at higher temperature, 60℃ increased the sensitivity of the test organisms to the plant extract. Phytochemical analysis indicated t/tat the plant possesses tannins, saponins as well as phenols. Conclusion: A scientific basis exists that the plant possesses antibacterial activity and it could be a probable source of therapeutic agent.

(±)-Zanthonitidine A,a Pair of Enantiomeric Furoquinoline Alkaloids from Zanthoxylum nitidum with Antibacterial Activity

A pair of new enantiomeric furoquinoline alkaloids,(±)-zanthonitidine A(1),together with nine known ones(2-10)were isolated from the radix of Zanthoxylum nitidum.Their chemical structures were elucidated based on the extensive spectroscopic analysis.The racemic mixture of 1 was separated by chiral column chromatography,and the absolute configurations of (+)-1 and(-)-1 were determined by the comparison of experimental and calculated electronic circular dichroism spectra.Antibacterial activities of compounds 1-9 were evaluated,and compounds(+)-1,(-)-1,3,7 and 8 showed antibacterial activities against Bacillus subtilis,Enterococcus faecalis or Staphylococcus aureus.

Synthesis and antibacterial activity of 4″-O-carbamoyl analogs of clarithromycin

A series of novel 4'-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-susceptible S.pneumoniae.Particularly,4-fluorobenzyl carbamate 7a demonstrated potent activity against erythromycin-resistant S.pneumoniae encoded by the mef gene,and remarkably improved activity against erythromycin-resistant S.pneumoniae encoded by the erm gene,and the erm and mef genes.

Novel dihydropyrazole derivatives linked with multi(hetero)aromatic ring:Synthesis and antibacterial activity

Eight novel heterocycle-substituted dihydropyrazole derivatives were synthesized and characterized by ESI-MS, ^1H NMR and ^13C NMR. All of the compounds have been screened for their antibacterial potential in vitro against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The results show that compounds 9b, 9g and 9h displayed significant activity with MIC values in the range of 0.39-1.562 μlmL against B. subtilis.

Synthesis and antibacterial activity of new layered perovskite compounds,Ag_xNa_(2-x)La_2Ti_3O_(10)

Three kinds of new layered perovskite compounds with Ruddlesden-Popper （R-P） phase, AgrNa2-xLa2Ti3O10 （x = 0.2, 0.3 and 0.5）, were synthesized by an ion-exchange reaction of Na2La2Ti3O10 with AgNO3 solution. The structures of the compounds were characterized by EDX and XRD, and their antibacterial activity and light-resistance property were evaluated. The results indicated that the molecular formula of AgxNa2-xLa2Ti3O10 （x = 0.2, 0.3 and 0.5） was confirmed, and that the crystalline structure of Na2La2Ti3O10 was not obviously affected by exchange of silver ion. The minimum inhibitory concentrations （MICs） of Ag0.3Na1.7La2Ti3O10 against Escherichia coli （E. coli）, Staphylococcus aureus （S. aureus） were 180 μg/mL and 240 μg/mL, respectively, while its discoloration was not observed after 24 h light ageing test.

Preparation of TiO_2 Thin Film and Its Antibacterial Activity

TiO 2 nanometer thin films with photocatalytic antibacterial activity were prepared by the sol-gel method on fused quartz and soda lime glass precoated with a SiO 2 layer.The thin films were characterized by X-ray photoelectron spectroscopy (XPS),scanning electron microscopy (SEM),and X-ray diffraction (XRD).The results show that sodium and calcium diffusion into nascent TiO 2 film is effectively retarded by the SiO 2 layer precoated on the soda lime glass.The antibacterial activity of the films was determined.The crystalline of TiO 2 nanometer thin film has important effects on the antibacterial activity of the film.

Synthesis, Crystal Structure and Antibacterial Activity of 4,4'-Hydrazine-1,2- diylidenebis(methanylylidene)bis(2-ethoxyphenol)

A new Schiff base compound, 4,4′-hydrazine-1,2-diylidenebis（methanylylidene）- bis（2- ethoxyphenol） （C18H20N2O4）, has been synthesized by the condensation of 3-ethoxy-4- hydroxybenzaldehyde and 80% hydrazine hydrate in an ethanol solution. The compound was characterized by 1H NMR, MS and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/n with a = 5.2421（5）, b = 10.3700（8）, c = 14.9906（11）A, β = 97.6030（10）°, Z = 2, V= 807.73（12） A, Dc = 1.350 g/cm3, Mr = 328.36, λ（MoKa） = 0.71073 A,μ = 0.096 mm-1, F（000） = 348, R = 0.041 and wR = 0.0136. The two benzene rings are coplanar. The molecule adopts an E,E configuration about the central C=N functional bonds. A total of 3938 unique reflections were collected, of which 1440 with I 〉 2σ（I） were observed. A different type of intermolecular hydrogen bond, O-H…N, exists in the crystal. The title complex molecules are connected through hydrogen bonds to generate a two-dimensional network. The preliminary antibacterial activity results showed that the title compound exhibits antibacterial activity against Staphylococcus aureus.

Synthesis, Crystal Structure and Antibacterial Activity of Two Hydrazones Derived from 2-Fluorobenzhydrazide

Two new Schiff base benzoyl hydrazone compounds, C14H10FN3O3 （Ⅰ） and C14H10F2N2O （Ⅱ）, have been synthesized and characterized by elemental analysis, IR, UV and X-ray single-crystal diffraction. Both compounds crystallize in monoclinic, space group P21/c with a = 7.0514（14）, b = 25.928（5）, c = 7.7099（15）, β = 111.823（2）°, V = 1308.6（4）3, Z = 4, C14H10FN3O3, Mr = 287.25, Dc = 1.458 g/cm3, μ（MoKα） = 0.115 mm-1, F（000） = 592, the final R = 0.0841 and wR = 0.2489 for 1901 observed reflections （I 2σ（I）） for I; a = 11.232（3）, b =12.735（4）, c = 8.612（2） , β = 90.869（3）°, V = 1231.7（6）3, Z = 4, C14H10F2N2O, Mr = 260.24, Dc = 1.403 g/cm3, μ（MoKα） = 0.111 mm-1, F（000） = 536, the final R = 0.0453 and wR = 0.1085 for 1317 observed reflections （I 2σ（I）） for Ⅱ. The antibacterial activities of both compounds against two bacteria were first studied and one compound showed considerable antibacterial activity against K. Pneumonia and S. aureus.

Preparation of Nano-TiO_2 by Liquid Hydrolysis and Characterization of Its Antibacterial Activity

The nano-TiO_2 particles were prepared by liquid hydrolysis method and characterized using XRD. Its antibacterial activity against two representative bacterial, Escherichia eoli and Staphylococcus aureus, was also studied. The experimental results showed that the nano-TiO_2 caleinated at 600-700℃ contained the obvious anatase phase and exerted exeeUent antibacterial activity. The feature of antibacterial activity of nano- TiO_2 was non-strains specificity and exerted best antibacterial activity at concentration of 0.8 g/L.

Determination of reactive oxygen generated from natural medicines and their antibacterial activity

Extracts of 16 natural medicine powders {Galla chinensis,Malloti cortex,Cassiae semen,Sophorae radix,Myricae cortex,Crataegi fructus,Gambit,Mume fructus,Geranii herba,Phellodendri cortex,Coptidis rhizoma,Swertiae herba,and Cinnamomi cortex） were assayed for reactive oxygen concentrations using the peroxyoxalate chemiluminescent detection system.High luminescence intensity was observed in Galla chinensis,Geranii herba,Malloti cortex,Myricae cortex,and Cinnamomi cortex.Additional experiments identified the reactive oxygen species as hydrogen peroxide.Galla chinensis generated 2.4 × 10^（-4） mol/L hydrogen peroxide from a 1 mg/mL solution.In bacterial growth tests,Galla chinensis extract had antibacterial activity against Escherichia coli.Staphylococcus aureus,Bacteroides thetaiotaomicron,Campylobacter sputorum biovar sputorum.Streptococcus salivarius thermophilus,Lactobacillus casei,and Bifidobacterium longum infantis.This antibacterial activity was decreased by the addition of catalase.It revealed that hydrogen peroxide which Galla chinensis produced participated in antibacterial activity.

Studies on Condensed Heterocyclic Compounds(Ⅲ)——Synthesis and Antibacterial Activity of 3-(4-Pyridyl)-6-Alkyl/Aromatic Heterocyclyl-s-Triazolo[3,4-b]-1, 3,4-Thiadiazoles and 1,4-Bis [6-(4-Pyridyl)-s-Triazolo [3,4-b]-1, 3,4-Thiadiazol-3-yl]-n-Butane

In recent years, fused heterocycles have been reported to possess important properties in synthesis and pharmacology. Especially, s-triazolo, 3,4-thiadiazole derivatives have been attracting much attention for chemists and pharmacologists because they show broad spectra of biological activities, such as antifungal, antibacterial, hy-

Conductive Polyaniline/Cellulose/Graphite Composite Films with High Thermal Stability and Antibacterial Activity

Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide monohydrate(NMMO) and regenerated in water to form the matrix. GP was dispersed in the NMMO solvent prior to the dissolution of the cellulose, and PANI was deposited on the surfaces of the cellulose/GP films by in situ chemical polymerization. The structures of the PANI/cellusose/GP composite films were investigated using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy(SEM), and SEM/energy-dispersive X-ray spectroscopy. The mechanical strengths, thermal stabilities, conductivities, and antibacterial activities of the films were studied in detail. The results showed that GP formed a multilayered structure in the cellulose matrix and that the PANI nanoparticles were tightly wrapped on the film surface. The film thickness increased from 40 mm to 100 mm after the addition of GP and PANI. The tensile strength of the composite films was 80~107 MPa, with the elongation at break being 3%~10%. The final residual weight of the composite films was as high as 65%, and the conductivity of the composite films reached 14.36 S/m. The cellulose matrix ensured that the films were flexible and exhibited desirable mechanical properties, while the GP filler significantly improved the thermal stability of the films. The PANI coating acted as a protective layer during burning and provided good electrical conductivity and antibacterial activity against Escherichia coli; both of these characteristics were slightly enhanced by the incorporation of GP. These PANI/cellulose/GP composite films should be suitable for use in electronics, antistatic packing, and numerous other applications.

Synthesis,Crystal Structure and Antibacterial Activity of a New Ternary Copper(Ⅱ) Complex with 2,6-Pyridinedicarboxylic Acid and 1,10-Phenanthroline

A new ternary copper（Ⅱ） complex, [C43H27Cu2N7O5][C14H6CuN2O8]＇6.5H2O, has been synthesized by the reaction of copper sulfate, 2,6-pyridinedicarboxylic acid and 1,10- phenanthroline （phen）, and characterized by elemental analysis, IR, UV and X-ray single-crystal diffraction. It crystallizes in triclinic, space group P1, with a = 14.379（5）, b = 15.510（5）, c = 15.835（6） A, a = 78.567（6）, β = 63.594（6）, y = 81.287（6）°, V= 3092.1（19） A3, C57H46Cn3N9O19.5, Mr = 1359.54, Z = 2, Dc = 1.446 Mg/m3, λ（MoKa） = 0.71073 A,μ = 1.101 mm^-1, F（000） = 1362, S = 1.071, the final R = 0.0718 and wR = 0.11960 for 10705 observer reflections （I 〉 2σ（I））. The structure unit of the title complex consisfs of a mononuclear part and a di-nuclear part, and the three copper ions show three coordination modes. Each 6-coordinated geometry of the Cu atom is a distorted octahedral coordination geometry. The 3D supramolecular system is formed by the hydrogen bond O-H-O and π-π stacking interaction between neighboring single cells. The antibacterial activity of the title complex is also studied.

In vitro Antibacterial Activity of Palmitoleic Acid Isolated from Filamentous Microalga Tribonema minus Against Fish Pathogen Streptococcus agalactiae

Filamentous microalgae from genus Tribonema are promising sustainable sources of omega-7 palmitoleic acid,but their ability to accumulate this compound varies among species and depends on the initial nitrogen concentration(INC)supply.In this study,the palmitoleic acid accumulation capacities of five Tribonema species were examined under three different INCs to select the alga species with the highest production.Results showed that a high INC was associated with increased palmitoleic acid accumulation but led to decreased biomass concentration in all tested species.In particular,T.minus grown at 18 mmol L^(−1)INC had the highest palmitoleic acid content(20.72%of dry weight)and productivity(90.88 mg L^(−1)d−1).The combination of alkali metal freezing precipitation(AMFP)and urea complexation successfully isolated and enriched palmitoleic acid from T.minus and obtained a purity of 80.11%and a yield of 7.39 g(100 g)^(−1) of algal powder.The compound was identified as(9Z)-hexadecenoic acid(C16:1ω-7).Antibacterial activity evaluation for the highly concentrated palmitoleic acid(10 mg mL^(−1))against Streptococcus agalactiae revealed the formation of a 12.10 mm-diameter inhibition zone and the minimum inhibitory concentration of 31.25μg mL^(−1),indicating that palmitoleic acid is an effective antibacterial agent.This study is the first to report that palmitoleic acid derived from T.minus can antagonize S.agalactiae,which further broadens the potential application of Tribonema biomass in green aquaculture.

Structure and Antibacterial Activity of Modified Montmorillonite

Tetradecyldimethylbenzyl ammonium salt（TDMBA） cations were intercalated into sodium montmorillonite（Na-MMT） by an ion exchange reaction. The resulting TDMBA-MMT was characterized by Fourier-transform infrared spectroscopy（FTIR）, thermogravimetric analysis（TGA）, and X-ray diffraction（XRD）. Moreover, the antibacterial activity and water-resistance of TDMBA-MMT were investigated. The results show that TDMBA cations are intercalated into the Na-MMT. The onset temperature of decomposition of TDMBA cations in TDMBA-MMT is raised about 60 ℃ higher than that of tetradecyldimethylbenzyl ammonium chloride（TDMBACl）, and the d（001） spacing enlarged from 1.23 nm to 2.10 nm. 0.1 mg/mL TDMBA-MMT is fully enough to kill all the Staphylococci aureus（S, aureus） and more than 99.99% of the Escherichia coli（E, coli） in a sample solution within 6.0 h touch, and the TDMBA-MMT also shows long acting properties.