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.

Identification and Antibacterial Activity Study of a Terrestrial Strain of Brevibacterium aureus 431

This study isolated and purified strain 431 from an animal probiotic product.Through staining and microscopic examination,colony morphology analysis,biochemical reaction tests,and 16S rDNA sequence alignment,the strain was identified and named Brevibacterium aureus 431.The study focused on the production of biosurfactants by strain 431,and antibacterial activity tests were conducted on the strain and its secondary metabolites.The results showed that strain 431 exhibited no resistance to 10 commonly used drugs,and its concentrated secondary metabolites were highly sensitive to the indicator bacterium Escherichia coli.Oral administration of strain 431 to BALB/c mice resulted in normal mental state,diet,and bowel movements,with no signs of illness or death,indicating that strain 431 is highly safe and non-pathogenic to mice.The study suggests that Brevibacterium aureus 431 has significant research value as a new source of actinomycetes and that its secondary metabolites have potential application value in the development of antibacterial drugs.

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.

Study on Pu-erh Tea Methanol Extracts on Antibacterial Activity of Several Plant Pathogens

[Objective] The aim was to study Pu-erh tea methanol extracts on antibacterial activity of several plant pathogens and provide reference for application of Pu-erh tea in agriculture disease prevention and control.[Method]The inhibitive effect of Pu-erh tea methanol extracts on several plant pathogens was studied by adopting mycelium growth rate method.[Result] The results showed that Pu-erh tea methanol extracts had inhibitive effects on Thanatephorus cucomeris(Frank)Donk,Fusarium oxysporum f.sp.niveum,Fusa...

Screening of Antagonistic Actinomyces against Soft Rot of Amorphophallus konjac and Its Antibacterial Activity

[Objective] Antagonistic actinomyces of Amorphophallus konjac soft rot were isolated from the soil,the antibacterial activity of the fermentation was detected,and its active components were separated.[Method] The antagonistic actinomycetes were screened using plate confrontation culture method.The SJK18 antagonistic strain with strong activity was conducted single-factor tests using different carbon sources,nitrogen sources,temperatures and pH value as the culture condition,and the antibacterial activities of fermentation liquid was determined,respectively.The fermentation liquid of antagonistic strain was extracted with alcohol and acetic ester,and their antibacterial activities were determined.[Result] A total of 112 strains of actinomycetes were obtained,and 11 strains had antibacterial activity.The antibacterial activity of SJK18 strain was the strongest in the single-factor test,when the corn powder was adopted as the carbon sources,KNO3 was the nitrogen source,the temperature was 30 ℃ and the pH was 6.0,the appropriate pH value for the activity was 5.5-10.0.The diameters of inhibition zone of alcohol extract and raffinate of ethyl acetate were 17.0 and 20.0 mm,respectively,while the extraction of ethyl acetate had no antibacterial activity.[Conclusion] A strain of actinomyces with strong antibacterial activity against soft rot of A.konjac was obtained.

Synthesis and Antibacterial Activity of (S)-5-(Heterocycle Methylene) -3-(3-Fluoro-4-morpholin-4-yl-phenyl)-Oxazolidin-2-one Derivatives

Aim To study the structure-activity relationship of antibacterial oxazolidinone derivatives. Methods Seven （S） -5- （ heterocycle methylene） -3- （3-fluoro-4-morpholin-4-yl-phenyl） -oxazoli- din-2-ones were synthesized by the substitution of （S）-[ 3-（3-fluoro-4-morpholin-4-yl-phenyl）-oxazohdin-2-one-5-yl]-methanol mesylate with some secondary amines and the structures of the product were confirmed by ^1H NMR and elemental analyses or MS. Results None of the seven compounds showed potent activity against the tested 20 strains of bacteria in vitro. Conclusion The replacement of 5- acetylaminometyl of Linezolid by 5-（heterocycle methylene） lost the antibacterial activity.

Correlation analysis between the HPLC fingerprints and in vitro antibacterial activity of ethyl acetate extracts from Radix isatidis

Aim To study the correlation between the HPLC fingerprints and in vitro antibacterial activities of EtOAc extracts of Radix isatidis from various sources. Methods Ten batches of Radix isatidis EtOAc extracts were analyzed with HPLC and the fingerprints were established. The influence of EtOAc extracts on the thermogenic curve of growth of Escherchia coli was obtained by microcalorimetry. The chemical differences of EtOAc extracts of Radix isatidis from various sources in the HPLC fingerprints were probed with hierarchical clustering analysis and similarity analysis. The correlation between the HPLC fingerprints and in vitro antibacterial activities was analyzed with multivafiant correlation analysis. Results Close correlation existed between the HPLC fingerprints and in vitro antibacterial activities of EtOAc extracts of Radix isatidis. Conlusion The combination of HPLC fingerprints and antibacterial activities can be used to discover principle components of Radix isatidis on bioactivity.

Antibacterial Activity of Herbal Preparations against Staphylococcus aureus and Streptococcus agalactiae in Cow Mastitis

[Objective] This study aimed to analyze the antibacterial activity of herbal preparations against Staphylococcus aureus and Streptococcus agalactiae in cow mastitis. [Method] The crude drug solutions of four different prescriptions for Zengrujianniusan were prepared through reflux extraction. Their antibacterial activity in vitro against Staphylococcus aureus and Streptococcus agalactiae in cow mastitis were investigated. [Result] All the four different prescriptions exhibited antibacterial activity against S. aureus and S. agalactiae. Among them, prescription Ⅲ was extremely sensitive, and had the best bactericidal effect. The other three prescriptions were highly sensitive. [Conclusion] This study provides a theoretical basis for the development of herbal preparations for the treatment of cow mastitis.

Chemical Compositions and Antibacterial Activity of Essential Oil from Thymus Seedlings of Tissue Culture

[Objective] This study aimed to compare and analyze the chemical compositions, the relative contents and the antibacterial activity of the essential oils extracted from the tissue culture seedlings, the aseptic seedlings and the common seedlings from seeds of Thymus vulgaris. [Method] The essential oil was extracted by steam distillation; the chemical compositions and their relative contents were analyzed by gas chromatography-mass spectrometry （GC/MS） and peak area normalization method; and the antimicrobial activity was tested by filter paper method. [Result] A total of 54 compositions were identified from these three samples, they had similar main compositions： thymol, m-Cymene, terpinene and so on, and these compositions were slightly different in contents. In addition, the essential oils from these three samples exhibited obvious antibacterial effect against Escherichia coli and Staphylococcus aureus, in which the antibacterial activity against S. aureus was stronger than against E. coli. [Conclusion] It is possible to produce essential oil by tissue culture technology; the main compositions and antibacterial activity of the oils remained almost the same.

Antibacterial Activity of Bacillus subtilis and Properties of Protein Crude Extract

In order to get biological drugs with no resistance or toxic side effects and to reduce the use of antibiotics, a strain of Baci//us subtilis was isolated from animal intestine, and the isolate was identified by molecular biological method; in vitro an- tibacterial test of the isolate was performed using agar diffusion method; the optimal fermentation condition of the isoJate was screened by conventional culture method; the antibacterial crude protein of the isolate was extracted by saturated ammonium sulfate method; the physicochemical properties of antibacterial crude protein was de- tected by comparison method; The results showed that the isolate was B. subti/is, which had antibacterial effects on Staphy/ococcus aureus, streptococcus and swine erysipelas. The fermentation effect of the isolate was the best under the condition of temperature 30 ~C, pH 7, liquid volume 75 ml/250 ml, inoculation volume 20% and culture time 48 h. The antibacterial effect of the isolate was the best when extract- ed by 80% saturated ammonium sulfate. The antibacterial crude protein had strong resistance to heat and acid. Organic solvent and UV irradiation had some influences on antibacterial crude protein. Proteases had hydrolytic effects on antibacterial crude protein. The isolated B. subti/is can be used to prevent and control the diseases caused by S. aureus, streptococcus and swine erysipelas, and can regulate intesti- nal microecology by adding into expanded feeds.

Determination of the Content of Total Alkaloids in Different Solvent Extracts from Climbing Groundsel Herb Produced in Guizhou Province and Their Antibacterial Activity

[Objective] This study aimed to compare the contents of total alkaloids in different solvent extracts from climbing groundsel herb produced in Guizhou Province and their antibacterial activity. [Method] The content of total alkaloids was measured by UV spectrophotometry, and Oxford cups were used to investigate the antibacterial activity of each solvent extract. [Result] There was a good linear correlation between the absorbance measured by the UV spectrophotometer and the content of total al- kaloids within the concentration of 0.011 0-0.054 8 mg/ml at 207 nm, and the re- gression equation was Y=23.654X＋0.021, R=0. 999 7 and the average recovery rate was 99.2%. The contents of total alkaloids in 60% ethanol extract, 95% ethanol and water ethanol were 38.71, 52.25 and 60.50 mg/g, respectively. The 60% ethanol ex- tract had strong antibacterial activity against Streptococcus pneumoniae, Staphylo- coccus aureus and Escherichia coil; the water extractive had stronger antibacterial activity against Escherichia colr, 95% ethanol extract had weak antibacterial activity, with no inhibition of Pseudomonas aeruginosa. [Conclusion] This method is accurate, simple, with good repeatability, which can be used for the determination of alkaloids content of the climbing groundsel herb; there is no positive correlation between the content of total alkaloids in different solvent extracts of climbing groundsel herb and their antibacterial activity.

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.

Bioactivity,in-vitro corrosion behavior,and antibacterial activity of silver-zeolites doped hydroxyapatite coating on magnesium alloy

Mg-based alloys received significant attention for temporary implant applications while, their applications have been limited by high degradation rate. Therefore, silver-zeolite doped hydroxyapatite（Ag-Zeo-HAp） coating was synthesized on Ti O2-coated Mg alloy by physical vapour deposition（PVD） assisted electrodeposition technique to decrease the degradation rate of Mg alloy. X-ray diffraction（XRD） analysis and field emission scanning electron microscopy（FE-SEM） images showed the formation of a uniform and compact layer of Ag-Zeo-HAp with a thickness of 15 μm on the Ti O2 film with a thickness of 1 μm. The potentiodynamic polarization（PDP） and electrochemical impedance spectroscopy（EIS） tests indicated that corrosion resistance of Mg-Ca alloy was considerably increased by the Ag-Zeo-HAp coating. The bioactivity test in the simulated body fluid（SBF） solution showed that a dense and homogeneous bonelike apatite layer was formed on the Ag-Zeo-HAp surface after 14 d. Investigation of antibacterial activity via disk diffusion and spread plate methods showed that the Ag-Zeo-HAp coating had a significantly larger inhibition zone（3.86 mm） towards Escherichia coli（E. coli） compared with the Ti O2-coated Mg alloy（2.61 mm）. The Ag-Zeo-HAp coating showed high antibacterial performance, good bioactivity, and high corrosion resistance which make it a perfect coating material for biomedical applications.

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.

Synthesis and evaluation of in vitro antibacterial activity of novel 2,5-disubstituted-l,3,4-thiadiazoles from fatty acids

A series of new 1-（alkenoyl/hydroxyalkenoyl）-4-benzoyl-thiosemicarbazides 2a-d and 2-benzamide-5-alkenyl/hydroxyalk- enyl-1,3,4-thiadiazoles 3a-d were synthesized from fatty acid hydrazides. Structure of all these compounds was confirmed by IR, IH NMR, Sac NMR, mass spectra and elemental analysis. The bioassay results indicate that some compounds 2e, 2d, 3e and 3d have good antibacterial activity.

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.

Morphology controlled synthesis of ZnO nanoparticles for in-vitro evaluation of antibacterial activity

Novel hierarchical flower-and nanorod-shaped ZnO nanoparticles with uniform morphological features were successfully synthesized through controlled precipitation method in aqueous media without using any surfactant or template.To elucidate the growth mechanism of the synthesized nanoparticles,the effects of pH,reaction time and temperature were studied systematically.Selected ZnO samples were then subjected to SEM,FT-IR and XRD analysis.XRD patterns confirmed well crystalline nature of the as-synthesized powders.Furthermore,synthesized nanoparticles(hierarchical flowers as ZnO-1 and nanorods as ZnO-2),as well as commercial ZnO(ZnO-Com),were then investigated for in-vitro evaluation of antibacterial activity against various bacterial strains of clinical importance.Results showed that ZnO-2 exhibited higher antibacterial activity to all tested strains than ZnO-1,while ZnO-Com showed no antibacterial response in the applied experimental conditions.In addition,ZnO concentration-dependent antibacterial study unfolded that size of inhibition zones increased significantly from^30 to 33 mm against Streptococcus mutans and from^28 to 30 mm against Escherichia coli with increasing ZnO-2 concentration from 0.25 to 0.75μg/μL.The present study,therefore,suggests that the application of synthesized ZnO nanoparticles as the antibacterial agent may be effective for inhibiting certain pathogenic bacteria in biomedical sides.

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.