芽孢杆菌CY1-3株碱性纤维素酶基因celC的克隆及其在大肠杆菌中的表达

芽孢杆菌CY1-3株基因组DNA经Sau3AⅠ部分消化后回收2~7 kb片段,构建了部分文库。通过刚果红染色鉴定,筛选出6个纤维素酶基因的阳性克隆子,经酶切鉴定为同一克隆子,命名为pGJc-1。经测序分析,该片段包含一个由1 593个核苷酸组成的开放阅读框(ORF),命名为celC。经推导,celC基因编码由一531个氨基酸残基组成的CelC蛋白。氨基酸序列分析表明,CelC蛋白的氨基酸序列与多种细菌的-β1,4-内切葡聚糖酶具有很高的同源性。粗酶液的SDS-PAGE分析表明,celC基因在大肠杆菌中所表达的CelC蛋白具有纤维素酶活力,其分子质量约为58 ku。     

红茂草生物碱抑菌活性的测定

用醇提法提取红茂草生物碱,经石英色谱柱层析分离、结晶后测定了红茂草生物碱对大肠杆菌、金黄色葡萄球菌、枯草杆菌、粪肠球菌的体外最小抑菌浓度(MIC)、抑菌率和半数抑菌浓度(IC50)。结果显示,红茂草生物碱对大肠杆菌、金黄色葡萄球菌、枯草杆菌、粪肠球菌的MIC分别是0.22、0.18、0.18、0.30mg/mL;对这4种供试菌的IC50分别是0.180 7、0.140 70、.140 70、.260 5 mg/mL。表明,红茂草生物碱对这4种细菌具有明显的抑制作用。     

炭疽杆菌基因检测技术的研究进展

从炭疽杆菌基因组组成、炭疽杆菌基因组的特征及其在基因检测中的应用几方面阐述了炭疽杆菌基因检测技术的研究进展,探讨了分别位于pXO1和pXO2质粒上的主要致病毒素编码基因pagAl、ef、cya和参与荚膜合成的主要蛋白编码基因capA、capB和capC的作用,认为这些炭疽杆菌特异基因序列是建立基因检测体系的可靠基础,其标志性序列有早期发现的序列指纹图谱、高度保守基因序列和最新发现的高度特异基因序列,基因检测方法从早期的RFLP、VNTR、单重PCR、多重PCR发展到最新的实时定量PCR,随着标志性序列特异性的增加和检测方法的改进,炭疽杆菌的诊断工作变得更加准确和快捷。     

枯草芽孢杆菌在防御动物疾病中的研究进展

结合国内外对枯草芽孢杆菌的研究结果,对枯草芽孢杆菌在拮抗病原菌、免疫刺激、芽孢疫苗及肠道内繁殖等方面的研究进展进行了综述,旨在为枯草芽孢杆菌在防御动物疾病中的深入研究提供参考。     

断奶仔猪胃肠道乳酸菌及芽孢杆菌的分离鉴定

为研制优良的猪用益生菌制剂,从断奶仔猪胃肠道分离乳酸菌和芽孢杆菌,结合细菌的形态特征、生理生化指标,运用16SrRNA基因序列分析方法对其进行了鉴定。结果表明,分离株WR、KR、HR、JR分别为胃、空肠、回肠、结肠源的唾液乳杆菌(Lactobacillus salivarius);ZR株为直肠源的约氏乳杆菌(Lactobacillus johnsonii);MR株为盲肠源的粪肠球菌(Enterococcus faecalis);分离株WY、SY、KY分别为胃、十二指肠、空肠源的枯草芽孢杆菌(Bacillus subtilis);HY株为回肠源的蜡样芽孢杆菌(Bacillus cere-us)。各分离株的生长曲线有明显差异,HR、ZR和WY株的生长速度较快,分别于接种后第12、12和20小时达到生长高峰期,显示了良好的培养特性。     

Detection of Anthrax and Other Pathogens Using a Unique Liquid Array Technology

A bead‐based liquid hybridization assay, Luminex^® 100?, was used to identify four pathogenic bacteria, Bacillus anthracis, Clostridium botulinum, Francisella tularensis subsp. tularensis, and Yersinia pestis, and several close relatives. Hybridization between PCR‐amplified target sequences and probe sequences (located within the 23S ribosomal RNA gene rrl and the genes related to the toxicity of each bacterium) was detected in single‐probe or multiple‐probe assays, depending on the organism. The lower limits of detection (LLDs) for the probes ranged from 0.1 to 10 ng. Sensitivity was improved using lambda exonuclease to digest the noncomplementary target strand. All contributors in 33 binary, ternary, and quaternary mixtures in which all components were present in a 1:1 ratio were identified with an 80% success rate. Twenty‐eight binary mixtures in which the two components were combined in various ratios were further studied. All target sequences were detected, even when the minor component was overshadowed by a tenfold excess of the major component.     

Composition of bacillus species in aerosols from 11 U.S. cities

A PCR-based heteroduplex assay was used to determine the presence and composition of Bacillus species in 11,059 Environmental Protection Agency PM2.5 aerosol samples from 11 U.S. cities. The assay differentiated three groups: Type A containing Bacillus anthracis and very closely related, often pathogenic, Bacillus cereus and Bacillus thuringiensis strains; Type B containing other B. cereus and B. thuringiensis strains; and a third group of more-distantly related Bacillus species. Eight of the 11 cities were positive for Bacillus species in 50% or more of the samples, and the percent of aerosol samples that contained the HD Type A group ranged from 3% to 32%. Cities from the eastern half of the United States generally contained a higher frequency and broader diversity of Bacillus species than the western half of the United States. Positive samples were detected throughout the year. These results have implications for pathogen detection in environmental samples, understanding the natural evolution of new pathogenic strains, and incidence of infection caused by strains of the B. cereus subgroup.     

Effect of Sterilants on Amplification and Detection of Target DNA from Bacillus cereus Spores

To conceal criminal activity of a bioterrorist or agroterrorist, the site of pathogen generation is often treated with sterilants to kill the organisms and remove evidence. As dead organisms cannot be analyzed by culture, this study examined whether DNA from sterilant‐treated Bacillus cereus spores was viable for amplification. The spores were exposed to five common sterilants: bleach, Sterilox®, oxidizer foam (L‐Gel), a peroxyacid (Actril®), and formaldehyde vapor. The spores were inoculated on typical surfaces found in offices and laboratories to test for environmental effects. It was found that the surface influenced the efficiency of recovery of the organisms. The DNA isolated from the recovered spores was successfully detected using RT‐qPCR for all treatments except for formaldehyde, by amplifying the phosphatidylinositol phospholipase C and sphingomyelinase genes. The results demonstrated that evidence from sites treated with sterilants can still provide information on the uncultured organism, using DNA amplification.     

Evaluation of Commercial‐off‐the‐Shelf Materials for the Preservation of Bacillus anthracis Vegetative Cells for Forensic Analysis,

Environmental surface sampling is crucial in determining the zones of contamination and overall threat assessment. Viability retention of sampled material is central to such assessments. A systematic study was completed to determine viability of vegetative cells under nonpermissive storage conditions. Despite major gains in nucleic acid sequencing technologies, initial positive identification of threats must be made through direct culture of the sampled material using classical microbiological methods. Solutions have been developed to preserve the viability of pathogens contained within clinical samples, but many have not been examined for their ability to preserve biological agents. The purpose of this study was to systematically examine existing preservation materials that can retain the viability of Bacillus anthracis vegetative cells stored under nonpermissive temperatures. The results show effectiveness of five of seventeen solutions, which are capable of retaining viability of a sporulation deficient strain of B. anthracis Sterne when stored under nonrefrigerated conditions.     

微生态制剂—XA1503菌粉的研制和应用

从5株不同的蜡状芽胞杆菌中筛选出XA1503菌株,并与市售“止痢灵”菌种DM423蜡状芽胞杆菌进行了毒性和安全性试验的比较,证明XA1503菌株是一株十分安全无害的菌。用XA1503菌株制成的菌粉,经实验室和临床试验结果表明,它是一种有效的微生态制剂,用于畜禽肠道疾病的预防和治疗,特别是仔猪、犊牛、羔羊、仔犬的腹泻、鸡白痢有明显效果。