新型肠毒素蛋白SElK编码基因的克隆测序、生物信息学分析和表达载体构建

采用微波加热法提取金黄色葡萄球菌基因组DNA,根据NCBI上登录的肠毒素基因sek设计引物,PCR克隆selk基因,对selk基因测序并进行生物信息学分析,在此基础上构建重组表达质粒p ET-32a(+)-selk.测序结果表明本研究克隆得到具有正确编码序列的新型肠毒素selk基因;Protparam分析表明在一级结构水平上该蛋白具有较高的热稳定性;亲疏水性分析表明SEl K蛋白是一个亲水性较高的蛋白质;同源建模表明SEl K蛋白的domain B结构域缺乏传统肠毒素所具有的胱氨酸环,但SEl K蛋白domain B中β-折叠片数量比传统肠毒素更高.这些结果为进一步研究SEl K蛋白的结构与功能奠定基础.     

Highly Stable,Amide‐Bridged Autoinducing Peptide Analogues that Strongly Inhibit the AgrC Quorum Sensing Receptor in Staphylococcus aureus

Blocking quorum sensing (QS) pathways has attracted considerable interest as an approach to suppress virulence in bacterial pathogens. Toward this goal, we recently developed analogues of a native autoinducing peptide (AIP‐III) signal that can inhibit AgrC‐type QS receptors and attenuate virulence phenotypes in Staphylococcus aureus. Application of these compounds is limited, however, as they contain hydrolytically unstable thioester linkages and have only low aqueous solubilities. Herein, we report amide‐linked AIP analogues with greatly enhanced hydrolytic stabilities and solubilities relative to our prior analogues, whilst maintaining strong potencies as AgrC receptor inhibitors in S. aureus. These compounds represent powerful tools for the study of QS.     

Antiinfective properties of ursolic acid-loaded chitosan nanoparticles against Staphylococcus aureus

The present study aimed to synthesize ursolic acid-loaded chitosan nanoparticles (UA-Ch-NPs) as an antiinfective agent against 21 Staphylococcus aureus isolates. The UA-Ch-NPs were synthesized by a simple method and then characterized by TEM, FTIR, DLS-zeta potential, and XRD analyses. According to the characterization results, highly dispersed spherical nanoparticles with a mean diameter of 258 nm and a zeta potential of + 40.1 mV were developed. The antibacterial properties of UA-Ch-NPs were investigated and their inhibitory effect on biofilm formation was demonstrated by AFM. Finally, the expression levels of icaA and icaD were measured using real-time PCR. Results indicated that the minimum inhibitory concentration (MIC) of UA and UA-Ch-NPs against S. aureus was 64 and 32 µg/mL, respectively. The treatment of bacterial cells with UA-Ch-NPs significantly decreased the expression of icaA and icaD genes which are engaged in biofilm formation. Our results indicated that UA-Ch-NPs could be a promising material for antibacterial and antibiofilm applications.     

响应曲面法优化超高压杀灭金黄色葡萄球菌条件的研究

 因子试验研究结果表明,显著影响超高压杀灭金黄色葡萄球菌效果的外界因子是温度、压力和保压时间。在此基础上,采用响应曲面法（Response Surface Methodology,RSM）建立了超高压杀灭金黄色葡萄球菌的二次多项数学模型,验证了模型的有效性,并探讨了上述3个因子的交互作用及其最佳水平范围,优化出杀灭6个数量级金黄色葡萄球菌ATCC6538的外界条件为：温度34.35 ℃,压力329.84 MPa,时间15.53 min。     

Rapid detection of Staphylococcus aureus by a combination of monoclonal antibody-coated latex and capillary electrophoresis

The rapid detection of pathogenic bacteria is extremely important in biotechnology and clinical diagnosis. CE has been utilized in the field of bacterial analysis for many years, but to some extent, simultaneous separation and identification of certain microbes from complex samples by CE coupled with UV detector is still a challenge. In this paper, we propose a new strategy for rapid separation and identification of Staphylococcus aureus (S. aureus) in bacterial mixtures by means of specific mAb-coated latex coupled with CZE. An appropriate set of conditions that selectively isolated S. aureus from the microorganisms Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae were established. S. aureus could be differentiated from the others by unique peaks in the electropherograms. The validity was also confirmed by LIF with antibodies specific to both the latex and the microbial cells. The LOD is as low as 9.0 x 10(5) colony forming unit/mL. We have also utilized this technology to identify S. aureus in a stool sample coming from a healthy volunteer spiked successfully with S. aureus. This CZE-UV technique can be applied to rapid diagnosis of enteritis caused by S. aureus or other bacterial control-related fields needing rapid identification of target pathogens from microbial mixtures. In theory, this method is suitable for the detection of any bacterium as long as corresponding bacterium-specific antibody-coated latex is available.     

微生物能力验证样品制备工艺及水产品企业水平测试结果评价

为了提高舟山市水产品企业实验室微生物检测能力,保证企业自检结果准确可靠,根据舟山市进出口检验检疫工作的特点,选取了水产品中3个常规的微生物检测项目,即菌落总数、副溶血弧菌和金黄色葡萄球菌检测,采用了真空冷冻干燥技术制备一系列微生物能力验证样品,对舟山市88家水产品企业的实验室进行微生物能力验证。结果表明采用本工艺制备的能力验证样品具有稳定性好、贮存方便、保存期长等优点。从水产品企业微生物水平测试结果来看,菌落总数项目的满意率为81.8%;副溶血弧菌检测的正确率为93.8%,而金黄色葡萄球菌检测的正确率为82.1%。检测结果存在偏差的主要原因是检测中未使用标准菌株进行参照、试剂在使用前无进行质量核查、对某些生化反应判断失误等。     

广西金斑喙凤蝶生物学特性初步观察及其保护

根据野外观察和已有的资料，初步研究广西珍稀濒危昆虫金斑喙凤蝶的生物学特性和保护对策，其活动范围较狭窄且稳定，生活周期短，是进行种群生存力分析较理想的物种，认为 及早进行定量分析，为政府的保护工作提供科学依据。     

兔葡萄球菌病的诊断和药敏试验

目的对家兔发病死亡的原因进行诊断。方法对病死家兔进行剖检观察,并进行细菌分离培养与生化鉴定、PCR检测和药敏试验。结果通过对病死家兔进行剖检观察、细菌分离培养、生化鉴定、血清学试验、PCR检测和药敏试验,确诊病死家兔是金黄色葡萄球菌感染引起的细菌性疾病。药敏试验结果表明,分离菌株对青霉素、氨苄西林、万古霉素等抗生素敏感,而对头孢他啶、呋喃妥因已产生耐药性。结论为金黄色葡萄球菌病原鉴定与疾病诊断提供了科学依据。     

聚合酶链反应检测石蜡切片中金黄色葡萄球菌DNA的研究

目的　探讨聚合酶链反应技术 (PCR)在检测石蜡包埋组织中金黄色葡萄球菌DNA的应用及价值。方法　利用PCR技术 ,对 55例福尔马林固定、石蜡包埋小鼠组织中SA DNA进行了检测。结果　 55例石蜡包埋的小鼠组织中均检测到SA DNA ,这与临床病理诊断为金黄色葡萄球菌 (S .aureus)感染相一致。结论　PCR技术可用于检测石蜡包埋组织中的SA DNA片段 ,为鼠S .aureus感染的回顾性分析提供了有效手段     

The Antibacterial Activity Mode of Action of Plantaricin YKX against Staphylococcus aureus

We aimed to evaluate the inhibitory effect and mechanism of plantaricin YKX on S. aureus. The mode of action of plantaricin YKX against the cells of S. aureus indicated that plantaricin YKX was able to cause the leakage of cellular content and damage the structure of the cell membranes. Additionally, plantaricin YKX was also able to inhibit the formation of S. aureus biofilms. As the concentration of plantaricin YKX reached 3/4 MIC, the percentage of biofilm formation inhibition was over 50%. Fluorescent dye labeling combined with fluorescence microscopy confirmed the results. Finally, the effect of plantaricin YKX on the AI-2/LuxS QS system was investigated. Molecular docking predicted that the binding energy of AI-2 and plantaricin YKX was −4.7 kcal/mol and the binding energy of bacteriocin and luxS protein was −183.701 kcal/mol. The expression of the luxS gene increased significantly after being cocultured with plantaricin YKX, suggesting that plantaricin YKX can affect the QS system of S. aureus.