鉴定金黄色葡萄球菌的凝固酶和A蛋白双标记胶乳试剂的研制和应用

研制了鉴定金黄色葡萄球菌的丙种球蛋白和血浆纤维蛋白原双重标记的胶乳试剂。检测临床标本分离的葡萄球菌295株,结果表明该胶乳试剂提高了金葡菌的检出率,且较简便快速。

Significantly enhanced photoelectrochemical cathodic protection performance and preventing biofouling dual functional Cu_(2)ZnSnS_(4)/TiO_(2)nanotube composite material

A new type of photoelectrochemical cathodic protection technology(a combination of seawater corrosion and biological fouling resistance)is being actively researched to alleviate the serious corrosion of marine metal materials.At present,there is almost no research on anti-corrosion and anti-fouling dual functional materials.In this paper,Cu_(2)ZnSnS_(4)is attached to the surface of TiO,nanotubes through a one-step hydrothermal method for modification.The results indicate that when the hydrothermal reaction time is 24 h,Cu_(2)ZnSnS_(4)/TiO_(2)nanocomposite material exhibits excellent performance in coupling with the protected 304 SS,with its open circuit potential shifts negatively to-1.04 V.This material improves the separation efficiency of photogenerated electrons and effectively improves the photochemical cathodic protection of 304 stainless steel.The high removal rate of Staphylococcus aureus(up to 93%)of the as-prepared samples also proved that it has the effect of the anti-biological fouling.

Temperature-Induced Unfolding Pathway of Staphylococcal Enterotoxin B:Insights from Circular Dichroism and Molecular Dynamics Simulation

In this study,circular dichroism(CD)and molecular dynamics(MD)simulation were used to investigate the thermal unfolding pathway of staphylococcal enterotoxin B(SEB)at temperatures of 298–371 and 298–500 K,and the relationship between the experimental and simulation results were explored.Our computational findings on the secondary structure of SEB showed that at room temperature,the CD spectroscopic results were highly consistent with the MD results.Moreover,under heating conditions,the changing trends of helix,sheet and random coil obtained by CD spectral fitting were highly consistent with those obtained by MD.In order to gain a deeper understanding of the thermal stability mechanism of SEB,the MD trajectories were analyzed in terms of root mean square deviation(RMSD),secondary structure assignment(SSA),radius of gyration(R_(g)),free energy surfaces(FES),solvent-accessible surface area(SASA),hydrogen bonds and salt bridges.The results showed that at low heating temperature,domain Ⅰ without loops(omitting the mobile loop region)mainly relied on hydrophobic interaction to maintain its thermal stability,whereas the thermal stability of domain Ⅱ was mainly controlled by salt bridges and hydrogen bonds.Under high heating temperature conditions,the hydrophobic interactions in domain Ⅰ without loops were destroyed and the secondary structure was almost completely lost,while domain Ⅱ could still rely on salt bridges as molecular staples to barely maintain the stability of the secondary structure.These results help us to understand the thermodynamic and kinetic mechanisms that maintain the thermal stability of SEB at the molecular level,and provide a direction for establishing safer and more effective food sterilization processes.

Two bacterial infection models in tree shrew for evaluating the efficacy of antimicrobial agents

Animal models are essential for the development of new anti-infectious drugs.Although some bacterial infection models have been established in rodents,small primate models are rare.Here,we report on two bacterial infection models established in tree shrew（Tupaia belangeri chinensis）.A burnt skin infection model was induced by dropping 5×106 CFU of Staphylococcus aureus on the surface of a wound after a third degree burn.This dose of S.aureus caused persistent infection for 7 days and obvious inflammatory response was observed 4 days after inoculation.A Dacron graft infection model,2×106 CFU of Pseudomonas aeruginosa also caused persistent infection for 6 days,with large amounts of pus observed 3 days after inoculation.These models were used to evaluate the efficacy of levofloxacin（LEV） and cefoperazone（CPZ）,which reduced the viable bacteria in skin to 4log10 and 5log10 CFU/100 mg tissue,respectively.The number of bacteria in graft was significantly reduced by 4log10 CFU/mL treatment compared to the untreated group（P0.05）.These results suggest that two bacterial infection models were successfully established in tree shrew using P.aeruginosa and S.aureus.In addition,tree shrew was susceptible to P.aeruginosa and S.aureus,thus making it an ideal bacterial infection animal model for the evaluation of new antimicrobials.

Inhibitory Effects of Bacillus subtilis on Staphylococcus aureus

[Objective] To produce drug resistance, seek non-toxic environmental so as to change the current biological drugs that did not excessive use of antibiotics. [Methods] A strain of Bacillus was purified and isolated from fresh and healthy in- testines of grass carps. Biochemical identification was carried out by conventional bacterial biochemical test method. Two pairs of primers were designed, 16S rRNA detection and sequencing analysis were carried out. Drug sensitive test was carried out by agar diffusion method. In vitro inhibition test on Staphylococcus aureus was carried out by Oxford cup method. [Results] The isolated bacterium had basically the same biochemical characters as Bacillus subtilis; and the homology reached 100%. Thus, the isolated bacterium was identified to be Bacillus subtilis. It was insensitive to amoxicillin, ampicillin, penicillin G and so on, but sensitive to amikacin, cefalexin, ciprofloxacin and cefradine. The inhibitory effects of Bacillus subtilis on Staphylococ- cus aureus were significant. The minimum inhibitory concentration （MIC） was 2.8×10^8×2^-5/ml and minimum bactericidal concentration （MBC） was 2.8×10^8×2^-2/ml. [Conclusions] The isolated Bacillus subtilis could be used to prevent and control diseases caused by Staphylococcus aureus, and reduce the abuse of antibiotics.

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.

Purification of Antimicrobial Peptide from Antarctic Krill (Euphausia superba) and its Function Mechanism

The preliminary purification and antimicrobial mechanism of antimicrobial peptide from Antarctic Krill were studied in this paper. The results showed that the molecular weight range of antimicrobial polypeptide （CMCC-1） obtained by cation exchange chromatography was between 245-709D as detected by molecular sieve chromatography, and the minimum inhibition concentration （MIC） of CMCC-1 against Staphylococcus aureus was 5.0mgmL^-1. The antimicrobial mechanism of CMCC-1 was studied with S. aureus as indicator bacterium. Compared with control group, the results of the experimental group in which S. aureus was treated with CMCC-1 were as follows： l） CMCC-1 could inhibit cell division at logarithmic phase. 2） The protein and reducing sugar con- tent, and the conductivity of culture medium increased, and the activity of alkaline phosphatase and [3-galactosidase could be detected in the culture medium. 3） Observation under scanning electron microscope revealed that somatic morphology became irregular, and then somatic surface became coarse. The cell became much smaller, and most somatic ceils gathered. The boundary between cells became dim and finally fused as a whole. 4） Observation under transmission electron microscope showed that the surface of S. aureus became rough and the reproducing ability was restrained. The cell wall became thin and the cytoplasm shrunk. Substances inside cell leaked out, which caused cells death. 5） SDS-PAGE analysis showed that some bands disappeared, and the residual bands became vague. 6） The genomic DNA electrophoresis results showed that the genomic DNA bands ofS. aureus were not degraded but the brightness significantly reduced. Thus, it is supposed that CMCC-1 could destroy the cell wall and membrane of S. aureu, increase the cell membrane permeability and the leaking-out of intracellular substances, and thus cause the death ofS. aureu.

Isolation and identification of symbiotic bacteria from the skin, mouth, and rectum of wild and captive tree shrews

Endosymbionts influence many aspects of their hosts’ health conditions, including physiology, development, immunity, metabolism, etc. Tree shrews(Tupaia belangeri chinensis) have attracted increasing attention in modeling human diseases and therapeutic responses due to their close relationship with primates. To clarify the situation of symbiotic bacteria from their body surface, oral cavity, and anus, 12 wild and 12 the third generation of captive tree shrews were examined. Based on morphological and cultural characteristics, physiological and biochemical tests, as well as the 16 S rDNA full sequence analysis, 12 bacteria strains were isolated and identified from the wild tree shrews: body surface: Bacillus subtilis(detection rate 42%), Pseudomonas aeruginosa(25%), Staphlococcus aureus(33%), S. Epidermidis(75%), Micrococcus luteus(25%), Kurthia gibsonii(17%); oral cavity: Neisseria mucosa(58%), Streptococcus pneumonia(17%); anus: Enterococcus faecalis(17%), Lactococus lactis(33%), Escherichia coli(92%), Salmonella typhosa(17%); whereas, four were indentified from the third generation captive tree shrews: body surface: S. epidermidis(75%); oral cavity: N.mucosa(67%); anus: L. lactis(33%), E. coli(100%). These results indicate that S. epidermidis, N. mucosa, L. lactis and E. coli were major bacteria in tree shrews, whereas, S. aureus, M. luteus, K. gibsonii, E. faecalis and S. typhosa were species-specific flora. This study facilitates the future use of tree shrews as a standard experimental animal and improves our understanding of the relationship between endosymbionts and their hosts.

Chemical profile of the secondary metabolites produced by a deep-sea sediment-derived fungus Penicillium commune SD-118

Bioassay-guided fractionation of the crude extract from Penicillium commune SD-118, a fungus obtained from a deep-sea sediment sample, resulted in the isolation of a known antibacterial compound, xanthocillin X (1), and 14 other known compounds comprising three steroids (2-4), two ceramides (5 and 6), six aromatic compounds (7-12), and three alkaloids (13-15). Xanthocillin X (1) was isolated for the first time from a marine fungus. In the bioassay, xanthocillin X (1) displayed remarkable antimicrobial activity against Staphylococcus aureus and Escherichia coli, and significant cytotoxicity against MCF-7, HepG2, H460, Hela, Du145, and MDA-MB-231 cell lines. Meleagrin (15) exhibited cytotoxicity against HepG2, Hela, Du145, and MDA-MB-231 cell lines. This is the first report of the cytotoxicity of xanthocillin X (1).

C-jun N-terminal Kinase-mediated Signaling Is Essential for Staphylococcus Aureus-induced U937 Apoptosis

Objective To investigate the effect of SP600125, a specific c-jun N-terminal protein kinase (JNK) inhibitor, on Staphylococcus aureus (S. aureus)-induced U937 cell death and the underlying mechanism. Methods The human monocytic U937 cells were treated with S. aureus at different time with or without SP600125. Cell apoptosis was analyzed by flow cytometry. JNK, Bax, and caspase-3 activities were detected by Western blotting. Results S. aureus induced apoptosis in cultured U937 cells in a time-dependent manner. Expression of Bax and phospho-JNK significantly increased in S. aureus-treated U937 cells, and the level of activated caspase-3 also increased in a time-dependent manner. Inhibition of JNK with SP600125 significantly inhibited S. aureus-induced apoptosis in U937 cells. Conclusions S. aureus can induce apoptosis in U937 cells by phosphorylation of JNK and activation of Bax and caspase-3. SP600125 protects U937 cells from apoptosis induced by S. aureus via inhibiting the activity of JNK.

Antibacterial activity of nanostructured Ti-45S5 bioglass-Ag composite against Streptococcus mutans and Staphylococcus aureus

Mechanical alloying and annealing at 1150 °C for 2 h under an argon atmosphere were used to prepare Ti-45S5 bioglass nanocomposites. Ti-45S5 bioglass material was chemically modified by silver. The antibacterial activity of Ti-10% 45S5 bioglass nanocomposite containing silver against Streptococcus mutans and Staphylococcus aureus was studied. Nanocomposites were characterized by X-ray diffraction, scanning electron microscopy equipped with an electron energy dispersive spectrometer and transmission electron microscopy to evaluate phase composition, crystal structure and grain size. In vitro bacterial adhesion study indicated a significantly reduced number of Streptococcus mutans and Staphylococcus aureus on the bulk nanostructured Ti-45S5 bioglass-Ag plate surface in comparison to that on microcrystalline Ti plate surface. Nanostructured Ti-based biomaterials can be considered to be the future generation of dental implants.

Phosphoinositide 3-Kinase/Akt and Nuclear Factor-κB Are Involved in Staphylococcus Aureus-induced Apoptosis in U937 Cells

Objective To explore the mechanisms involved in Staphylococcus aureus （S. aureus） invading human monocytic U937 cells. Methods S. aureus were added to U937 cells at multiplicity of infections （MOI） of 20：1 for 0, 15, 30, 60, and 90 minutes, respectively. Cell apoptosis was analyzed with Hoechst 33258 staining and Annexin V-fluorescein isothiocyanate （FITC）/propidium iodide （PI） flow cytometry analysis. Akt and nuclear factor-κB （NF-κB） activities were detected by Western blotting. Results Infection of U937 cells with S. aureus induced rapid cell death in a time-dependent manner, and the cells displayed characteristic features of apoptosis. S. aureus-induced apoptosis was associated with a prominent downregulation of activated （phosphorylated） Akt and NF-κB. The inhibition of phosphorylated Akt by LY294002 led to the inhibition of NF-κB in a dose-dependent manner. Inhibition of Akt with LY294002 caused further increase in apoptosis of U937 cells. Conclusions S. aureus can stimulate the apoptosis of U937 ceils. S. aureus induces apoptosis of U937 cells by inhibiting Akt-regulated NF-κB.

Alkaloids from an algicolous strain of Talaromyces sp.

Compounds isolated and identified in a culture of the alga-endophytic fungus Talaromyces sp. cf- 16 included two naturally occurring alkaloids, 2-[（S）-hydroxy（phenyl）methyl]-3-mcthylquinazolin-4（3H）- one （la） and 2-[（R）-hydroxy（phenyl）methyl]-3-methylquinazolin-4（3H）-one （lb）, that were identified for the first time. In addition, seven known compounds （2-8） were obtained from the culture. Following chiral column chromatography, compounds la and lb were identified as enantiomers by spectroscopic analyses and quantum chemical calculations. Bioassay results showed that 5 was more toxic to brine shrimp than the other compounds, and that 3-6 could inhibit Staphylococcus aureus.

Lactobacillus species shift in distal esophagus of high-fat-diet-fed rats

AIM： To analyze the microbiota shift in the dista esophagus of Sprague-Dawley rats fed a high-fat diet. METHODS： Twenty Sprague-Dawley rats were divided into high-fat diet and normal control groups of 10 rats each. The composition of microbiota in the mucosa from the distal esophagus was analyzed based on se- lective culture. A variety of Lactobacillus species were identified by molecular biological techniques. Bacterial DNA from Lactobacillus colonies was extracted, and 165 rDNA was amplified by PCR using bacterial uni- versal primers. The amplified 16S rDNA products were separated by denaturing gradient gel electrophoresis （DGGE）. Every single band was purified from the gel and sent to be sequenced. RESULTS： Based on mucosal bacterial culturing in the distal esophagus, Staphylococcus aureus was absent, and total anaerobes and Lactobacillus species were de- creased significantly in the high-fat diet group compared with the normal control group （P 〈 0.01）. Detailed DGGE analysis on the composition of Lactobacillus species in the distal esophagus revealed that Lactobacillus crispa- tus, Lactobacillus gasseri （L. gasser/] and Lactobacillus reuteri （L. reuterl] comprised the Lactobacillus species in the high-fat diet group, while the composition of Lactobacillus species in the normal control group consisted of L. gasseri, Lactobacillus jensenii and L. reuteri. CONCLUSION： High-fat diet led to a mucosal micro- flora shift in the distal esophagus in rats, especially the composition of Lactobacillus species.

Antimicrobial Activity of Ulva reticulata and Its Endophytes

Seaweeds are known to exhibit various antimicrobial properties, since it harbours an enormous range of indigenous bioactive compounds. The emergence of drug resistant strains has directed to the identification of prospective metabolites from seaweed and its endophytes, thereby exploiting the properties in resisting bacterial diseases. The current study was aimed to assess the antimicrobial activity of extracts obtained from Ulva reticulate, for which metabolites of Ulva reticulata and its endophytes were extracted and assessed against human pathogens like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Bacillus subtilis. It was observed that the hexane extract of isolate VITDSJ2 was effective against all the tested pathogens but a significant inhibition was observed for Staphylococcus aureus and Escherichia coli. Further, Gas chromatography coupled with Mass spectroscopy （GC-MS） revealed the existence of phenol, 3, 5-bis （1, 1-dimethylethyl） in the crude hexane extract which is well-known to possess antibacterial activity. The effective isolate VITDSJ2 was identified to be the closest neighbour of Pseudomonas smtzeri by phenotypic and genotypic methods. The crude extracts of the seaweed Ulva reticulata was also screened for antibacterial activity and the hexane extract was effective in showing inhibition against all the tested pathogens. The compound in the crude extract of Ulva reticulata was identified as hentriacontane using GC-MS. The extracts obtained from dichloromethane did not show significant activity in comparison with the hexane extracts. Hence the metabolites of Ulva reticulata and the bacterial secondary metabolites of the endophytes could be used in the treatment of bacterial infections.

Extracts from Chinese Seabuckthorn Berry Have Antimicrobial Activity in vitro

Chinese seabuckthorn berry contains functional components. The berry was extracted by ethanol-water solution. MTT assay and growth rate method were applied to determine antibacterial ability in vitro of the extract solution. The antibacterial and antifungal assay indicated that the extract exhibited different degree of inhibitory activity. The result showed that the extract at a concentration of 1 250 mg/L had the maximum inhibitory effect against Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. Inhibitory effect against B. subtilis was much larger than that against the other two bacterial species. MIC values(minimum inhibitory concentration) of the extract on three bacterial species were 5 000, 1 250, and 1 000 mg/L respectively. IC_(50)(50% inhibiting concentration) evaluation of Trichoderma viride, Rhizopus stolonifer, Aspergillus niger, Penicillium expansum, and Vintage Red indicated that the berry had the strongest inhibitory effect against P. expansum(5 520 mg/L), while it had the weakest inhibitory effect against R. stolonifer(18 870 mg/L). The results proved that seabuckthorn berry had highly effective and comprehensive antimicrobial function.

Chitosan Extends the Shelf-life of Filleted Tilapia (Oreochromis niloticus) During Refrigerated Storage

Shelf-life extension of aquatic products is of significant economical importance. To determine the potential effect of chitosan on the shelf-life of filleted tilapia, this study analyzed the bacterial community diversity in fresh and spoiled tilapia fillets stored at (4 ± 1)℃ and examined the antimicrobial activity of chitosan against relevant bacteria isolates. Results showed that Pseudomonas (20%) and Aeromonas (16%) were abundant in fresh tilapia fillets, whereas Pseudomonas (52%), Aeromonas (32%) and Staphylococcus (12%) were dominant in the spoiled samples. Chitosan showed wide-spectrum antibacterial activity against bacteria isolated from tilapia and 5.0 g L-1 chitosan was selected for application in preservation. We further determined the shelf-life of chitosan-treated, filleted tilapia stored at (4 ± 1)℃ based on microbiological, biochemical and sensory analyses. Results showed that the shelf-life of chitosan-treated, filleted tilapia was extended to 12 d, whereas that of untreated, control samples was 6 d. These indicate that chitosan, as a natural preservative, has great application potential in the shelf-life extension of tilapia fillets.

Synthesis and Antimicrobial Activity of Boron-doped Titania Nano-materials

Antibacterial activity of boron-doped TiO2(B/TiO2) nano-materials under visible light irradiation and in the dark was investigated. A simple sol-gel method was used to synthesize TiO2 nano-materials. X-ray diffraction pattern of B/TiO2 nano-materials represents the diffraction peaks relating to the crystal planes of TiO2(anatase and rutile). X-ray photoelectron spectroscopy result shows that part of boron ions incorporates into TiO2 lattice to form a possible chemical environment like Ti O B and the rest exist in the form of B2O3. The study on antibacterial effect of B/TiO2 nano-materials on fungal Candida albicans(ATCC10231), Gram-negative Escherichia coli(ATCC25922) and Gram-positive Staphylococcus aureus(ATCC6538) shows that the antibacterial action is more significant on Candida albicans than on Escherichia coli and Staphylococcus aureus. Under visible light irradiation, the antibacterial activity is superior to that in the dark.

Bacterial diversity in the intestine of young farmed puffer fish Takifugu rubripes

The aim of the study was to examine the bacterial community associated with the intestinal mucus of young farmed puffer fish Takifugu rubripes. Polymerase chain reaction and partial 16 S r DNA sequencing was performed on DNA from bacteria cultivated on Zobell 2216 E medium. All the isolates were classified into two phyla—Proteobacteria and Firmicutes. Proteobacteria were the dominant, culturable intestinal microbiota(68.3%). At the genus level, V ibrio, Enterobacter, Bacillus, Pseudomonas, Exiguobacterium, Staphylococcus, Acinetobacter, Pseudoalteromonas and S hewanella were isolated from the intestine, with representatives of the genera V ibrio, Enterobacter and Bacillus accounting for 70.7% of the total. This is the first report of Enterobacter, Bacillus, Exiguobacterium and Staphylococcus as part of the intestinal bacterial microflora in T. rubripes. The profile of the culturable bacterial community differed between samples collected from the same tank at 2-month intervals, as indicated by Bray-Curtis and Sorensen indices, and the impact on the intestinal physiology and health of puffer fish requires further investigation.

Characterization of a Bacteriocin-Like Substance Produced from a Novel Isolated Strain of Bacillus subtilis SLYY-3

In the present research, the strain SLYY-3 was isolated from sediments of Jiaozhou Bay, Qingdao, China. The strain SLYY- 3, which produced a bacteriocin-like substance （BLS）, was characterized to be a strain of Bacillus subtillis by biochemical profiling and 16S rDNA sequence analysis. It is the first time to report that Bacillus subtilis from Jiaozhou Bay sediments could produce a BLS. The BLS of B. subtillis SLYY-3 exhibited strong inhibitory activity against gram-positive bacteria （including Staphylococcus aureus and B. subtillis） and some fimgi （including Penicillium glaucum, Aspergillus niger and Aspergillus flavus）. The antimicrobial activity was detected from culture in the exponential growth phase and reached its maximum when culture entered into stationary growth phase. It was thermo-tolerant even when being kept at 100~C for 60 min without losing any activity and stable over a wide pH range from 1.0 to 12.0 while being inactivated by proteolytic enzyme and trypsin, indicating the proteinaceous nature of the BLS. The BLS was purified by precipitation with hydrochloric acid （HC1） and gel filteration （Sephadex G-100）. SDS-PAGE analysis of the extracellular peptides of SLYY-3 revealed a bacteriocin-like protein with a molecular mass of 66 kDa. Altogether, these characteristics indicate the potential of the BLS for food industry as a protection against pathogenic and spoilage microorganisms.