竹醋液馏分杀菌效果的研究实验

为测定在不同条件下蒸馏分离竹醋液得到的各种馏分的灭菌效果,按照定量杀菌实验标准并以浓度与作用时间等等因素对金黄色葡萄球菌进行试验.结果表明:在19~21℃时,体积浓度为2∶11的馏分Ⅰ、馏分Ⅳ及竹醋原液对于金黄色葡萄球菌,均有显著的杀菌作用(杀菌率>90%).杀菌剂最佳作用时间为10 min,四种馏分的杀菌效果与竹醋原液比较,其中三种馏分杀菌率不及竹醋原液,仅有一种主要成分为醋酸的馏分Ⅰ,其杀菌效果较突出.     

Antibacterial Effect of Silver-Titanium Bimetallic Nano-Materials

Abstract

In order to study the antimicrobial effect of silver - titanium bimetallic nano-materials, in this study, through the preparation of TiO₂ particles, then using the photoprecipitation method, TiO₂/Ag composite materials are synthesized, and finally the core-shell structure of TiO₂-Ag nano-composite materials are prepared. The prepared nano-materials are characterized and analyzed. Common Escherichia coli and Staphylococcus aureus are used to evaluate their antimicrobial properties. The results show that there is a maximum absorption peak at 335?nm for TiO₂ particles, and the ultraviolet absorption spectra of TiO₂/Ag composites and core-shell structure of TiO₂-Ag nano-composites change unevenly. The stability of core-shell nano-composites of TiO₂-Ag is good and its optical properties are better than expected. The appearance characterization of the prepared nano-materials is analyzed. It is found that the appearance of the prepared nano-materials is basically uniform, and the Ag ions in the core-shell structure of the nano-composites are well dispersed, uniform in size and ideal in effect. In X-ray diffraction analysis, it is found that there are four additional peaks in the TiO₂/Ag composite and core-shell structure of the TiO₂-Ag nano-composites compared with the TiO₂. This is due to the fusion of Ag particles and the fact that Ag particles are not oxidized in the process of ultraviolet irradiation. In the analysis of the antimicrobial properties of the prepared nano-materials, it is found that the antimicrobial effect is most obvious when the reaction time is 45?min, the reaction temperature is 20?°C and the pH of the system is 6. Therefore, through this study, it is found that the antibacterial properties of nano-materials prepared by silver-titanium bimetallic fusion have obvious effect, which reaches the expectation of this study. Although there are some shortcomings in the research process, it still provides experimental basis for the later period of nano-materials with antimicrobial properties, and has important research significance.     

Growth of Staphylococcus aureus as Related to 17O NMR Water Mobility and Water Activity

¹⁷O NMR data were determined for three solute-BHI (Brain Heart Infusion) mixtures. For each solute, NaCl, raffinose and glycerol, NMR data (linewidths and signal intensity) were determined as well as water activity (a_w), moisture contents, and effects on growth of Staphylococcus aureus in media of various moisture contents. Liquid (highly mobile) water content in all media tested was determined by NMR. This mobile water was important and had a stronger correlation with S. aureus growth rate than did a_w or moisture content, although solute effects limited empirical prediction. NMR linewidth also correlated with lag phase.     

Selective Capture and Identification of Methicillin-Resistant Staphylococcus aureus by Combining Aptamer-Modified Magnetic Nanoparticles and Mass Spectrometry

A nucleic acid aptamer that specifically recognizes methicillin-resistant Staphylococcus aureus (MRSA) has been immobilized on magnetic nanoparticles to capture the target bacteria prior to mass spectrometry analysis. After the MRSA species were captured, they were further eluted from the nanoparticles and identified using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). The combination of aptamer-based capture/enrichment and MS analysis of microorganisms took advantage of the selectivity of both techniques and should enhance the accuracy of MRSA identification. The capture and elution efficiencies for MRSA were optimized by examining factors such as incubation time, temperature, and elution solvents. The aptamer-modified magnetic nanoparticles showed a capture rate of more than 90% under the optimized condition, whereas the capture rates were less than 11% for non-target bacteria. The as-prepared nanoparticles exhibited only a 5% decrease in the capture rate and a 9% decrease in the elution rate after 10 successive cycles of utilization. Most importantly, the aptamer-modified nanoparticles revealed an excellent selectivity towards MRSA in bacterial mixtures. The capture of MRSA at a concentration of 10² CFU/mL remained at a good percentage of 82% even when the other two species were at 10⁴ times higher concentration (10⁶ CFU/mL). Further, the eluted MRSA bacteria were successfully identified using MALDI mass spectrometry.     

牙膏抑菌效果分析研究

初步研究牙膏对大肠杆菌、金黄色葡萄球菌、绿脓杆菌三种比较常见致病菌的抑制效果,检验牙膏抑菌合格与否。用"抗菌有效性"方法,研究LP、MP、HP、LP-HE、LP-BA五种牙膏抑菌效果。LP牙膏中三种细菌浓度维持在106cfu/mL以上,其余四种牙膏在第14天后没有细菌生长,其中MP在4个周期5次检验中都没有细菌生长,LP-BA有类似抑菌效果,但第2次检验时,金黄色葡萄球菌和大肠杆菌的浓度分别为4×104cfu/mL和35×104cfu/mL,HP与LP-H有类似抑菌效果,在第2次检验时仅大肠杆菌生长,细菌浓度分别为1×106cfu/mL和2×106cfu/mL。LP牙膏不能对实验细菌起到抑制作用,而其余四种牙膏能有效的抑制细菌增长。     

氯化钠对几种常见菌的抑制作用

文章主要研究了NaCl对几种常见菌的抑制作用,设计了梯度平板实验和肉汤增值实验.梯度平板实验表明:很低的NaCl浓度就能抑制假丝酵母和乳酸杆菌生长;NaCl溶液浓度大约在5%以下对大肠杆菌具有抑制作用;浓度大约为8.5%的NaCl溶液对金黄色葡萄球菌具有抑制作用.肉汤增值实验表明:浓度4%的NaCl溶液对大肠杆菌具有抑制作用,浓度1.5%的NaCl溶液对乳酸杆菌和假丝酵母具有明显抑制杀灭作用,浓度7.5%的NaCl溶液对枯草芽孢杆菌具有抑制作用,浓度10%的NaCl溶液对金黄色葡萄球菌具有抑制作用.实验结果为NaCl抑菌作用提供了数据支持,所设计的实验方法为进一步开展NaCl杀菌抑菌作用的研究奠定了基础.     

脱镁叶绿酸a对金黄色葡萄球菌、大肠杆菌的抑制作用

以叶绿素为提取物，进行化学修饰得到光敏活性剂-脱镁叶绿酸α，其对微生物生长影响的研究表明：在光照条件下，脱镁叶绿酸α对金黄色葡萄球菌的生长和大肠杆菌原生质体的再生有明显的抑制作用；在暗培养条件下，脱镁叶绿酸α的抑制作用减弱。     

A note on the incidence and antibiotic resistance of Staphylococcus aureus isolated from meat and chicken samples

One hundred and fifty samples of raw calf/lamb meat samples (mince and chunks) and chicken parts (giblets, carcass) were analysed for the presence of Staphylococcus aureus. Eighty S. aureus strains were isolated and identified. Resistance of the strains to methicillin and other antibiotics was determined by the Kirby-Bauer disc diffusion test. The overall methicillin resistance rate for S. aureus was 67.5%. Of S. aureus strains, 87.5% were resistant to bacitracin. A high prevalence of penicillin G resistance was detected for S. aureus (53.8%). Few of the strains were resistant to erythromycin (7.5%). All strains were susceptible to vancomycin, sulbactam–ampicillin, ciprofloxacin and cefaperazone–sulbactam. This study confirmed the presence of S. aureus, especially antibiotic-resistant strains, in the foods examined, indicating poor sanitary conditions during processing which may create a health risk for consumers.     

靶序列富集多重PCR结合DHPLC同时检测5种食源性致病菌

目的建立同时检测沙门氏菌、单核细胞增生李斯特氏菌、大肠埃希氏菌O157、金黄色葡萄球菌和志贺氏菌5种食源性致病菌的简便、灵敏的高通量方法。方法根据GenBank公布的5种致病菌的特异性靶基因序列,设计5对特异性引物,与通用引物连接构成复合引物。经过反应条件的优化,建立了5种致病菌的靶序列富集多重PCR(target enriched multiplex PCR,Tem-PCR)扩增方法,扩增产物采用变性高效液相色谱(denaturing high-performance liquid chromatography,DHPLC)技术进行检测。结果采用Tem-PCR-DHPLC方法,检测48株试验菌株,未发现非特异性结果。对5种致病菌检测灵敏度,除金黄色葡萄球菌为620 cfu/mL外,其余都小于100 cfu/mL。对4种样品的检测结果与国家标准方法相符合。结论 Tem-PCR-DHPLC检测方法,相比传统多重PCR方法,能有效地解决引物扩增效率不均衡的问题,不需优化引物浓度,方法特异性强,灵敏度高,具有较好的实用性。     

产毒金葡菌和粘质沙雷氏菌在蘑菇罐头中的生长及产毒、产TECRA阳性物质的规律

本文研究了产毒金葡菌(Staphylococcus aureus)、粘质沙雷氏菌(Serrolia marcescens)的纯培养物,以及pH条件变化时,它们各自与其它细菌共存时,在蘑菇罐头中的生长及产葡萄球菌肠毒素、产TECRA阳性物质的规律。并了解热处理对肠毒素和阳性物质的效应。结果表明,金葡菌和粘质沙雷氏菌均能在蘑菇罐头中生长,并产毒/产阳性物质,但罐头汤汁的pH较有利于后者的生长和产阳性物质。在混合菌相中,金葡菌是虚弱竞争者,生长及产毒均受抑制。粘质沙雷氏菌所产阳性物质与肠毒素一样,具有一定的热抗性。