多粘类芽孢杆菌极端嗜热多肽的纯化及性质研究

用加热法从多粘类芽孢杆菌(Paenibacillus polymyxa)LM–3菌株的发酵液中纯化得到2个极端嗜热多肽。平板拮抗实验表明,5μL纯化多肽对稻瘟病菌(Magnaporthe grisea)抑菌率达89.6%。SDS–PAGE电泳显示纯化多肽分子量介于6000～7000u之间。多肽复性后,其中之一对稻瘟病菌表现出强的拮抗活性,命名为APPLM3(Antagonism Polypeptide from Paenibacillus polymyxa LM–3);另一个则无此活性,命名为PPLM3(Polypeptide from Paenibacillus polymyxaLM–3)。APPLM3经氨基酸测序,获得了其N–末端5个氨基酸序列(H2N–ANDPR);以该序列为靶序列在NCBI上进行相似性检索,发现其可能与3个假设蛋白(或推导蛋白)相关。APPLM3为首次报道的兼具极端嗜热性和稻瘟病菌拮抗活性的小分子多肽。     

污水厂污泥中病原微生物控制技术研究进展

污水厂污泥中存在大量病原微生物,若不加以控制,会给环境带来潜在的风险和威胁,因此研究污泥中病原微生物的控制技术具有重要意义.污泥的常规控制技术有堆肥、消化等,但在控制病原微生物方面却有局限性.近年来,利用蚯蚓堆肥、生物沥浸、射线激发、氧化等技术来控制污泥中的病原微生物的研究取得进展,部分技术在实践中也得到了一定的应用,但对病原微生物的灭活机理尚需要进一步研究.     

活性炭净水工艺微生物安全性研究

采用基于16SrDNA的焦磷酸测序法对北京某水厂活性炭净水工艺各单元的细菌群落结构进行分析。结果显示,砂滤对细菌多样性影响较小,活性炭工艺使菌群多样性升高。活性炭颗粒上的细菌群落结构与各工艺出水差异明显。α,β和γ变形菌纲是工艺出水和活性炭上的优势菌,活性炭池可以有效去除α变形菌纲和γ变形菌,但加氯消毒后的出厂水中α变形菌纲比例很高。出厂水中的第一优势菌为嗜氢菌属,含量高达86.2%。出厂水和活性炭颗粒上发现了9种潜在致病菌,如短波单胞菌、黄色单胞菌和鞘氨醇单胞菌等,但相对丰度较低,对饮用水安全影响较小。     

病原微生物和水处理

人类许多疾病可通过水来传播,而水传播疾病的爆发会对社会构成很大威胁.饮用水处理的目的正是提供给人们安全无病菌的饮用水.简要介绍了病原微生物的特点、对人类健康的危害性,比较了不同消毒剂对病原微生物的灭活作用,提出了去除病原微生物的工艺.引起疾病的微生物种类很多,包括细菌、病毒和原生动物,后者如隐孢子虫和贾第虫等.为灭活病原微生物,除了优化常规水处理工艺外,可采用臭氧、二氧化氯、紫外线、膜滤法等,当隐孢子虫卵囊的污染严重时,还应考虑附加处理工艺.     

Biofire Filmarray下呼吸道试剂盒在危重症新型冠状病毒肺炎继发感染患者中的应用效果评价

目的探讨Biofire Filmarry下呼吸道试剂盒(pneumonia panel, PN)在危重症COVID-19继发感染患者中的应用效果。方法回顾性分析2020年2月至4月武汉同济医院中法新区ICU危重症COVID-19患者的临床资料。经支气管镜获取患者肺泡灌洗液后分别送检Biofire Filmarray PN/普通培养,比较两种方法的检测结果,并计算其一致率。结果共21例符合纳入标准的危重症COVID-19患者入选本研究,送检下呼吸道标本54份,包括Biofire Filmarray PN组21例患者33份(61.1%)标本、普通培养组14例患者21份(38.9%)标本,其中19对(共38份)为两种方法"背靠背"送检。Biofire Filmarray PN组结果回报时间约为1 h,20例患者32份(97.0%)阳性标本,检出病原体74例次,其中鲍曼不动杆菌复合体29例次(39.2%),铜绿假单胞菌21例次(28.4%),肺炎克雷伯菌16例次(21.6%),大肠杆菌5例次(6.8%),阴沟肠杆菌、流感嗜血杆菌及呼吸道合胞病毒各1例次(1.4%)。普通培养组结果回报时间约为3 d,11例患者16份(76.2%)阳性标本,检出病原体19例次,其中为铜绿假单胞菌8例次(42.1%),鲍曼不动杆菌6例次(31.6%),嗜麦芽窄食单胞菌4例次(21.1%),粘金黄杆菌1例次(5.3%)。19对"背靠背"送检标本中,Biofire Filmarray PN组和普通培养组结果吻合者为15对,一致率为78.9%。结论危重症COVID-19患者易继发感染,病原体以鲍曼不动杆菌复合体、铜绿假单胞菌多见。Biofire Filmarray PN可用于此类患者的下呼吸道病原学诊断,具有回报速度快的优势,但其灵敏度需大样本研究进一步验证。     

Characterization of an Endolysin Targeting Clostridioides difficile That Affects Spore Outgrowth

Clostridioides difficile is a spore-forming enteric pathogen causing life-threatening diarrhoea and colitis. Microbial disruption caused by antibiotics has been linked with susceptibility to, and transmission and relapse of, C. difficile infection. Therefore, there is an urgent need for novel therapeutics that are effective in preventing C. difficile growth, spore germination, and outgrowth. In recent years bacteriophage-derived endolysins and their derivatives show promise as a novel class of antibacterial agents. In this study, we recombinantly expressed and characterized a cell wall hydrolase (CWH) lysin from C. difficile phage, phiMMP01. The full-length CWH displayed lytic activity against selected C. difficile strains. However, removing the N-terminal cell wall binding domain, creating CWH_351—656, resulted in increased and/or an expanded lytic spectrum of activity. C. difficile specificity was retained versus commensal clostridia and other bacterial species. As expected, the putative cell wall binding domain, CWH_1—350, was completely inactive. We also observe the effect of CWH_351—656 on preventing C. difficile spore outgrowth. Our results suggest that CWH_351—656 has therapeutic potential as an antimicrobial agent against C. difficile infection.     

Scientific Status Summary

The Institute of Food Technologists has issued this Scientific Status Summary to provide readers with a tutorial on biofilms, their purposeful mechanism of interaction (quorum sensing), and recent findings on how to inhibit their formation.     

一种芽孢蛋白对主要葡萄病菌抑制作用的研究

本试验采用平板法,研究供试茅孢蛋白对4种主要葡萄病害:白腐病、炭疽病、灰霉病和黑痘病的抑菌效果.结果表明,抑菌蛋白用量为150 μL,培养6d后,对4种病菌均有明显的抑菌效力,白腐病、炭疽病、灰霉病和黑痘病菌的抑菌圈直径分别为1.354cm,1.356cm,1.416cm和1.449cm.     

Antibacterial effects of American cranberry (Vaccinium macrocarpon) concentrate on foodborne pathogens

Antibacterial effects of American cranberry (Vaccinium macrocarpon) concentrate on foodborne pathogens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, and Staphylococcus aureus in vitro were investigated. Cranberry concentrate at various concentrations was prepared in distilled water (DW) or Brain Heart Infusion (BHI) broth. Pathogens were inoculated in each sample and incubated at 21 and 4 °C for 0, 1, 5, 7, and 24 h (DW samples) and 0, 1, 3, and 5 days (BHI samples). Transmission electron microscopy (TEM) was used to study the effects of cranberry concentrate on cellular structure of pathogens. DW results showed that S. Typhimurium and L. monocytogenes were reduced to non-detectable levels at 5 h in 100 μl/ml treatment at 21 and 4 °C. At 24 h, no target pathogens were detected from the 100 μl/ml treatment. BHI data indicated that the 100 μl/ml treatment reduced the four pathogens by 3-8 log CFU/ml compared with the control on Day 5 at 21 and 4 °C. TEM revealed damage to the bacterial cell walls and membranes. Cranberry concentrate has antibacterial effects on the four foodborne pathogens. Based on potential health benefits and proven antimicrobial effects, American cranberry concentrate may have dual applications as a food preservative.