This work was supported by grants from the Academic Research Fund of the Ministry of Education, and the National Medical Research Council and the National Research Foundation, Singapore.

生物膜的形成A. 1.结晶紫定量鲍曼不动杆菌 S1 <ol><li>成长5 ml培养A的杆菌中的S1 LB培养基（LB）（胰蛋白胨10克/升，酵母提取物5克/升），在30℃下在振荡培养箱（220转）16小时。 </li><li>调整A.文化杆菌 S1至所希望的OD 600为0.8。使用96孔板，接种细菌培养物（1:100稀释）到新鲜LB含有10微升纯化GKL酶（40毫克/毫升）的;新的文化的最终体积为100微升。 </li><li>准备控制文化为好;这将不包含任何酶。重复类似的状况以产生重复的期望数量。 </li><li>覆盖板用盖，并放入一个密封的10升塑料容器中。前轻轻取出介质孵育板在30℃下3小时。 </li><li>添加另外100微升新鲜LB培养基到井和孵育板21小时，在30℃。 </li&gt; <li>孵化的第二阶段后，轻轻取出所有的媒体。洗净的浮游细菌细胞用200微升无菌水。确保有清洗期间只有最小干扰细胞中。 </li><li>加入100微升的1％结晶紫溶液至每个孔，并孵育15分钟，在RT。通过洗涤井用200μl无菌水去除结晶紫溶液。重复洗两次。 </li><li>加入100微升33％乙酸至每个孔，并孵育15分钟，轻轻摇动;这会溶解染料。 </li><li>定量生物膜的通过测量结晶紫的吸光度在600nm处形成的量。结晶紫的量是成比例的生物膜的形成的量。 </li></ol> A. 2.激光共聚焦显微镜鲍曼不动杆菌 S1生物膜<ol><li>成长5 ml培养A的杆菌中的S1的LB在30℃在振荡培养箱（220rpm下）16小时。 </li><li>广告A的只是培养杆菌 S1至所希望的OD 600为0.8。使用35毫米的玻璃底μ-盘子，接种细菌培养物（1:100稀释）到新鲜LB含有30微升纯化GKL酶（40毫克/毫升）的;新的文化的最终体积为1毫升</li><li>覆盖μ-盘用盖子，并将其放置在一个密封的10升塑料容器中。前轻轻取出介质孵育μ-盘在30℃下3小时。添加30微升纯化GKL酶和新鲜培养基，将它带到1毫升的总体积。孵育另外21小时，在30℃。 </li><li>重复步骤2.3孵育μ-菜另外24小时在30℃。然后，轻轻地取出介质。 </li><li>加入500微升5微克/毫升阿莱克斯的Fluo 488缀合的麦胚凝集素（WGA）溶于Hank平衡盐溶液（HBSS）到μ-盘和孵育在37℃，30分钟;这会污染形成的生物膜。除去染色液和洗涤吨他μ-菜用2毫升的HBSS。重复该洗涤步骤一次。 </li><li>加入500微升3.7％的甲醛溶解在HBSS中，37℃，30分钟;这将解决生物膜到μ-菜。用2毫升的HBSS洗μ-菜一次，然后彻底删除解决方案。 μ-盘固定生物膜可以在4℃之前CLSM成像储存在黑暗中。 </li><li>对于激光共聚焦显微镜成像和分析，用63倍的放大倍率，产生97堆栈每幅图像，每堆0.21微米的间隔。 </li></ol>

<ol>
	<li>Alanis, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resistance+to+antibiotics:+are+we+in+the+post-antibiotic+era?.">Resistance to antibiotics: are we in the post-antibiotic era?.</a> Archives of medical research. 36, 697-705 (2005).</li><li>Cegelski, L., Marshall, G. R., Eldridge, G. R., Hultgren, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biology+and+future+prospects+of+antivirulence+therapies.">The biology and future prospects of antivirulence therapies.</a> Nature reviews. Microbiology. 6, 17-27 (2008).</li><li>LaSarre, B., Federle, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploiting+quorum+sensing+to+confuse+bacterial+pathogens.">Exploiting quorum sensing to confuse bacterial pathogens.</a> Microbiology and molecular biology reviews : MMBR. 77, 73-111 (2013).</li><li>Waters, C. M., Bassler, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quorum+sensing:+cell-to-cell+communication+in+bacteria.">Quorum sensing: cell-to-cell communication in bacteria.</a> Annual Review of Cell and Developmental Biology. 21, 319-346 (2005).</li><li>Rasko, D. A., Sperandio, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anti-virulence+strategies+to+combat+bacteria-mediated+disease.">Anti-virulence strategies to combat bacteria-mediated disease.</a> Nature reviews. Drug discovery. 9, 117-128 (2010).</li><li>Lazar, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quorum+sensing+in+biofilms--how+to+destroy+the+bacterial+citadels+or+their+cohesion/power?.">Quorum sensing in biofilms--how to destroy the bacterial citadels or their cohesion/power?.</a> Anaerobe. 17, 280-285 (2011).</li><li>Costerton, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bacterial+Biofilms:+A+Common+Cause+of+Persistent+Infections.">Bacterial Biofilms: A Common Cause of Persistent Infections.</a> Science. 284, 1318-1322 (1999).</li><li>Perez, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+challenge+of+multidrug-resistant+Acinetobacter+baumannii.">Global challenge of multidrug-resistant Acinetobacter baumannii.</a> Antimicrob Agents Chemother. 51, 3471-3484 (2007).</li><li>Tay, S. B., Yew, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+quorum-based+anti-virulence+therapeutics+targeting+Gram-negative+bacterial+pathogens.">Development of quorum-based anti-virulence therapeutics targeting Gram-negative bacterial pathogens.</a> International journal of molecular sciences. 14, 16570-16599 (2013).</li><li>Igarashi, J., Suga, H., Rumbaugh, K. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch.+19.">Ch. 19.</a> Quorum Sensing. 692, 265-274 (2011).</li><li>Ng, F. S., Wright, D. M., Seah, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+a+phosphotriesterase-like+lactonase+from+Sulfolobus+solfataricus+and+its+immobilization+for+disruption+of+quorum+sensing.">Characterization of a phosphotriesterase-like lactonase from Sulfolobus solfataricus and its immobilization for disruption of quorum sensing.</a> Applied and environmental microbiology. 77, 1181-1186 (2011).</li><li>Stacy, D. M., Welsh, M. A., Rather, P. N., Blackwell, H. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Attenuation+of+quorum+sensing+in+the+pathogen+Acinetobacter+baumannii+using+non-native+N-Acyl+homoserine+lactones.">Attenuation of quorum sensing in the pathogen Acinetobacter baumannii using non-native N-Acyl homoserine lactones.</a> ACS chemical biology. 7, 1719-1728 (2012).</li><li>Chow, J. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Directed+evolution+of+a+thermostable+quorum-quenching+lactonase+from+the+amidohydrolase+superfamily.">Directed evolution of a thermostable quorum-quenching lactonase from the amidohydrolase superfamily.</a> The Journal of biological chemistry. 285, 40911-40920 (2010).</li><li>Chow, J. Y., Yang, Y., Tay, S. B., Chua, K. L., Yew, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disruption+of+biofilm+formation+by+the+human+pathogen+Acinetobacter+baumannii+using+engineered+quorum-quenching+lactonases.">Disruption of biofilm formation by the human pathogen Acinetobacter baumannii using engineered quorum-quenching lactonases.</a> Antimicrobial Agents and Chemotherapy. 58, 1802-1805 (2014).</li><li>Pour, N. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilm+formation+by+Acinetobacter+baumannii+strains+isolated+from+urinary+tract+infection+and+urinary+catheters.">Biofilm formation by Acinetobacter baumannii strains isolated from urinary tract infection and urinary catheters.</a> FEMS immunology and medical microbiology. 62, 328-338 (2011).</li></ol>

The authors declare that they have no competing financial interests.

在这两组实验中，A杆菌 S1中培养在LB培养基无氯化钠作为高盐浓度可减少生物膜由细菌15形成的量。这种伪影的存在可能会低估生物膜的形成的量，以及仲裁 - 淬火酶在不同的处理条件的影响。使用催化失活酶是重要的，作为阴性对照，以消除酶封存的可能影响。 图1表明，即使不活动酶螯合仲裁分子，生物膜的形成不被中断。 鲍曼不动杆菌</em...

对于感染性疾病的治疗方案已被复杂化在多药耐药性细菌是免疫广泛的抗生素药物1的快速增加。从耐药细菌介导的感染的高发病率和死亡率，有必要升级药物开发过程和/或探索更好抗菌替代改善的治疗选择。近来，抗毒性的方法是获得给出其在经由非杀菌方法防止致病潜力的兴趣，因此减轻耐药机制2的风险。 群体感应是细菌毒力和这种信号中断现象的一个"总开关"是对发病3一个有前途的抗毒性的方法。毒力的发作需要仲裁分子在细胞外环境中的积累达到临界细菌种群密度之后。由于现状朗姆酒分子扩散回进入胞内基质中，与它们的同源受体结合导致的毒力因子的活化，以及与抗生素抗性和生物膜形成4相关的基因。在一般情况下，群体感应中断涉及抑制仲裁分子和受体相互作用，而不会影响主代谢途径。因此，它不具有对细胞生长的任何直接含意。由于健康不受损害，是最小的选择压力细菌进化并获得对这种治疗5阻力。此外，群体感应中断可以与固有的细菌保护机制干扰，如在生物膜形成，它提供了保护从抗菌剂和宿主免疫反应的情况下。 据估计，在复杂的生物膜状矩阵存在99％地球上的微生物，赋予关键存活优势居住在第微生物ESE结构6。更重要的是，形成这些无柄域是最持久和慢性医院获得性感染7的原因。 鲍曼不动杆菌是一个与全球医院获得性感染相关联，其毒力在很大程度上归因于群体感应的主要的人类病原体之一介导的生物膜形成8。仲裁淬酶已被成功地用于通过靶向一组化合物已知为 N -酰基高丝氨酸内酯（信号分子）是由革兰氏阴性细菌产生的9扰乱仲裁介导的信号转导。一些研究也扩大于使用这些酶通过毒力因子的表达和细胞数在生物膜10,11减少到方框细菌发病机理。不幸的是，仍缺乏有效利用仲裁 - 淬火酶对生物膜形成由细菌病原体扪示范的。该重新已经尝试使用定额抑制剂（AHL类似物）代替法定淬火酶，以破坏A.鲍曼不动杆菌生物膜形成12。虽然使用小分子抑制剂的这种方法是一种有效的方法，维持在平利用其生物利用度可能是一个挑战。与此相反，使用催化仲裁 - 淬火酶可以规避生物利用度问题，因为酶是朝固定上用于治疗效果的生物医学装置的表面更适合。 在这里，我们描述了从地芽孢kaustophilus（GKL）13对细菌生物膜的形成工程定额淬火lactonases的影响进行评估，采用结晶紫染色和激光共聚焦扫描显微镜（CLSM）。这项研究是生物膜分裂的在一个临床相关的A中的第一次成功的示范鲍曼不动杆菌菌株S1采用定额淬火酶。的方法中所述在这项研究中的用于评估对致病性革兰氏阴性细菌后续治疗的努力发展其他仲裁淬火酶的效力是有用的。

<table border="0" cellpadding="0" cellspacing="0" width="780">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Tryptone&#160;</td>
			<td style="width:151px;">BD</td>
			<td style="width:132px;">211705</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Yeast Extract</td>
			<td style="width:151px;">BD</td>
			<td style="width:132px;">212750</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">96-well plate</td>
			<td style="width:151px;">Costar</td>
			<td style="width:132px;">3596</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Crystal Violet</td>
			<td style="width:151px;">Sigma-Aldrich</td>
			<td style="width:132px;">C6158</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Acetic Acid</td>
			<td style="width:151px;">Lab-Scan</td>
			<td style="width:132px;">PLA00654X</td>
			<td>Caution: Flammable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#956;-Dish</td>
			<td style="width:151px;">Ibidi</td>
			<td style="width:132px;">80136</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Alex Fluo 488-conjugated WGA</td>
			<td style="width:151px;">Invitrogen</td>
			<td style="width:132px;">W11261</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hank&#8217;s balanced salt solution&#160;</td>
			<td style="width:151px;">Invitrogen</td>
			<td style="width:132px;">141475095</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Formaldehyde</td>
			<td style="width:151px;">Sigma-Aldrich</td>
			<td style="width:132px;">F8775</td>
			<td>Caution: Corrosive&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Synergy HT Microplate Reader</td>
			<td style="width:151px;">BioTek</td>
			<td style="width:132px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">1X-81 Inverted Fluorescence Microscope</td>
			<td style="width:151px;">Olympus</td>
			<td style="width:132px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

anti-virulent disruption of pathogenic biofilms using engineered quorum-quenching lactonases

The rapid emergence of multi-drug resistant bacteria has accelerated the need for novel therapeutic approaches to counter life-threatening infections. The persistence of bacterial infection is often associated with quorum-sensing-mediated biofilm formation. Thus, the disruption of this signaling circuit presents an attractive anti-virulence strategy. Quorum-quenching lactonases have been reported to be effective disrupters of quorum-sensing circuits. However, there have been very few reports of the effective use of these enzymes in disrupting bacterial biofilm formation. This protocol describes a method to disrupt biofilm formation in a clinically relevant A. baumannii S1 strain through the use of an engineered quorum-quenching lactonase. Acinetobacter baumannii is a major human pathogen implicated in serious hospital-acquired infections globally and its virulence is attributed predominantly to its biofilm's tenacity. The engineered lactonase treatment achieved significant A. baumannii S1 biofilm reduction. This study also showed the possibility of using engineered quorum-quenching enzymes in future treatment of biofilm-mediated bacterial diseases. Lastly, the method may be used to evaluate the competency of promising quorum-quenching enzymes.

在结晶紫定量实验中，两名仲裁淬火酶用于演示的可行性破坏生物膜的形成:野生型GKL和改进的GKL双突变体（E101G / R230C）。两种酶已显示表明内酯酶活性对3-羟基癸酰基-L-高丝氨酸内酯（3-OH-C 10 -HSL），使用由 A.主要仲裁分子鲍曼不动杆菌 S1 14。为生物膜分裂的有效评估，它们各自的无催化活性的酶（先前表明不螯合AHL配体）也包括在内作为立...

Watch this Scientific Journal Video about Anti-virulent Disruption of Pathogenic Biofilms using Engineered Quorum-quenching Lactonases at JoVE.com

Anti-virulent Disruption of Pathogenic Biofilms using Engineered Quorum-quenching Lactonases

Quorum-quenching enzymes are anti-virulent and anti-bacterial options that can mitigate pathogenesis without risk of incurring resistance, by preventing the expression of virulence factors and genes associated with antibiotic resistance and biofilm formation. In this study, we report a method that demonstrates the efficacy of quorum-quenching enzymes in bacterial biofilm disruption.

病原生物膜利用工程定额淬Lactonases防有毒中断

The rapid emergence of multi-drug resistant bacteria has accelerated the need for novel therapeutic approaches to counter life-threatening infections. The ...

anti-virulent-disruption-pathogenic-biofilms-using-engineered-quorum

Research

JoVE Journal

Immunology and Infection

10.5K 次观看.  Yong Loo Lin School of Medicine. Quorum-quenching enzymes are anti-virulent and anti-bacterial options that can mitigate pathogenesis without risk of incurring resistance, by preventing the expression of virulence factors and genes associated with antibiotic resistance and biofilm formation. In this study, we report a method that demonstrates the efficacy of quorum-quenching enzymes in bacterial biofilm disruption.

视频: Anti-virulent Disruption of Pathogenic Biofilms using Engineered Quorum-quenching Lactonases

Single-cell Analysis of Bacillus subtilis Biofilms Using Fluorescence Microscopy and Flow Cytometry

Biofilm formation is a general attribute to almost all bacteria 1-6. When bacteria form biofilms, cells are encased in extracellular matrix that is mostly constituted by proteins and exopolysaccharides, among other factors 7-10. The microbial community encased within the biofilm often shows the differentiation of distinct subpopulation of specialized cells 11-17. These subpopulations coexist and often show spatial and temporal organization within the biofilm 18-21.
Biofilm formation in the model organism Bacillus subtilis requires the differentiation of distinct subpopulations of specialized cells. Among them, the subpopulation of matrix producers, responsible to produce and secrete the extracellular matrix of the biofilm is essential for biofilm formation 11,19. Hence, differentiation of matrix producers is a hallmark of biofilm formation in B. subtilis.
We have used fluorescent reporters to visualize and quantify the subpopulation of matrix producers in biofilms of B. subtilis 15,19,22-24. Concretely, we have observed that the subpopulation of matrix producers differentiates in response to the presence of self-produced extracellular signal surfactin 25. Interestingly, surfactin is produced by a subpopulation of specialized cells different from the subpopulation of matrix producers 15.
We have detailed in this report the technical approach necessary to visualize and quantify the subpopulation of matrix producers and surfactin producers within the biofilms of B. subtilis. To do this, fluorescent reporters of genes required for matrix production and surfactin production are inserted into the chromosome of B. subtilis. Reporters are expressed only in a subpopulation of specialized cells. Then, the subpopulations can be monitored using fluorescence microscopy and flow cytometry (See Fig 1).
The fact that different subpopulations of specialized cells coexist within multicellular communities of bacteria gives us a different perspective about the regulation of gene expression in prokaryotes. This protocol addresses this phenomenon experimentally and it can be easily adapted to any other working model, to elucidate the molecular mechanisms underlying phenotypic heterogeneity within a microbial community.

Single-cell Analysis of Bacillus subtilis Biofilms Using Fluorescence Microscopy and Flow Cytometry

Microbial biofilms are generally constituted by distinct subpopulations of specialized cells. Single-cell analysis of these subpopulations requires the use of fluorescent reporters. Here we describe a protocol to visualize and monitor several subpopulationswithin B. subtilis biofilms using fluorescence microscopy and flow cytometry.

单细胞分析枯草芽孢杆菌生物膜，用荧光显微镜和流式细胞仪

Biofilm formation is a general attribute to almost all bacteria 1-6. When bacteria form biofilms, cells are encased in extracellular matrix that is mostly ...

科研

免疫与感染

Growth of Mycobacterium tuberculosis Biofilms

Mycobacterium tuberculosis, the etiologic agent of human tuberculosis, has an extraordinary ability to survive against environmental stresses including antibiotics. Although stress tolerance of M. tuberculosis is one of the likely contributors to the 6-month long chemotherapy of tuberculosis 1, the molecular mechanisms underlying this characteristic phenotype of the pathogen remain unclear. Many microbial species have evolved to survive in stressful environments by self-assembling in highly organized, surface attached, and matrix encapsulated structures called biofilms 2-4. Growth in communities appears to be a preferred survival strategy of microbes, and is achieved through genetic components that regulate surface attachment, intercellular communications, and synthesis of extracellular polymeric substances (EPS) 5,6. The tolerance to environmental stress is likely facilitated by EPS, and perhaps by the physiological adaptation of individual bacilli to heterogeneous microenvironments within the complex architecture of biofilms 7.
In a series of recent papers we established that M. tuberculosis and Mycobacterium smegmatis have a strong propensity to grow in organized multicellular structures, called biofilms, which can tolerate more than 50 times the minimal inhibitory concentrations of the anti-tuberculosis drugs isoniazid and rifampicin 8-10. M. tuberculosis, however, intriguingly requires specific conditions to form mature biofilms, in particular 9:1 ratio of headspace: media as well as limited exchange of air with the atmosphere 9. Requirements of specialized environmental conditions could possibly be linked to the fact that M. tuberculosis is an obligate human pathogen and thus has adapted to tissue environments. In this publication we demonstrate methods for culturing M. tuberculosis biofilms in a bottle and a 12-well plate format, which is convenient for bacteriological as well as genetic studies. We have described the protocol for an attenuated strain of M. tuberculosis, mc27000, with deletion in the two loci, panCD and RD1, that are critical for in vivo growth of the pathogen 9. This strain can be safely used in a BSL-2 containment for understanding the basic biology of the tuberculosis pathogen thus avoiding the requirement of an expensive BSL-3 facility. The method can be extended, with appropriate modification in media, to grow biofilm of other culturable mycobacterial species.
Overall, a uniform protocol of culturing mycobacterial biofilms will help the investigators interested in studying the basic resilient characteristics of mycobacteria. In addition, a clear and concise method of growing mycobacterial biofilms will also help the clinical and pharmaceutical investigators to test the efficacy of a potential drug.

Growth of Mycobacterium tuberculosis Biofilms

Mycobacterium tuberculosis forms drug tolerant biofilms when cultured in certain conditions. Here we describe methods for culturing M. tuberculosis biofilms and determining the frequency of drug tolerant persisters. These protocols will be useful for further studies into the mechanisms of drug tolerance in M. tuberculosis.

增长结核分枝杆菌生物膜

Mycobacterium tuberculosis, the etiologic agent of human tuberculosis, has an extraordinary ability to survive against environmental stresses including ...

Use of Image Cytometry for Quantification of Pathogenic Fungi in Association with Host Cells

Studies of the cellular pathogenesis mechanisms of pathogenic yeasts such as Candida albicans, Histoplasma capsulatum, and Cryptococcus neoformans commonly employ infection of mammalian hosts or host cells (i.e. macrophages) followed by yeast quantification using colony forming unit analysis or flow cytometry. While colony forming unit enumeration has been the most commonly used method in the field, this technique has disadvantages and limitations, including slow growth of some fungal species on solid media and low and/or variable plating efficiencies, which is of particular concern when comparing growth of wild-type and mutant strains. Flow cytometry can provide rapid quantitative information regarding yeast viability, however, adoption of flow cytometric detection for pathogenic yeasts has been limited for a number of practical reasons including its high cost and biosafety considerations. Here, we demonstrate an image-based cytometric methodology using the Cellometer Vision (Nexcelom Bioscience, LLC) for the quantification of viable pathogenic yeasts in co-culture with macrophages. Our studies focus on detection of two human fungal pathogens: Histoplasma capsulatum and Candida albicans. H. capsulatum colonizes alveolar macrophages by replicating within the macrophage phagosome, and here, we quantitatively assess the growth of H. capsulatum yeasts in RAW 264.7 macrophages using acridine orange/propidium iodide staining in combination with image cytometry. Our method faithfully recapitulates growth trends as measured by traditional colony forming unit enumeration, but with significantly increased sensitivity. Additionally, we directly assess infection of live macrophages with a GFP-expressing strain of C. albicans. Our methodology offers a rapid, accurate, and economical means for detection and quantification of important human fungal pathogens in association with host cells.

Here, we demonstrate how image cytometry can be used for quantification of pathogenic fungi in association with host cells in culture. This technique can be used as an alternative to CFU enumeration.

使用的细胞图像分析仪量化致病真菌与宿主细胞协会

Studies of the cellular pathogenesis mechanisms of pathogenic yeasts such as Candida albicans, Histoplasma capsulatum, and Cryptococcus neoformans ...

Concurrent Quantification of Cellular and Extracellular Components of Biofilms

Confocal laser scanning microscopy (CLSM) is a powerful tool for investigation of biofilms. Very few investigations have successfully quantified concurrent distribution of more than two components within biofilms because: 1)&#160;selection of fluorescent dyes having minimal spectral overlap is complicated, and 2)&#160;quantification of multiple fluorochromes poses a multifactorial problem. Objectives: Report a methodology to quantify and compare concurrent 3-dimensional distributions of three cellular/extracellular components of biofilms grown on relevant substrates. Methods: The method consists of distinct, interconnected steps involving biofilm growth, staining, CLSM imaging, biofilm structural analysis and visualization, and statistical analysis of structural parameters. Biofilms of Streptococcus mutans (strain UA159) were grown for 48 hr on sterile specimens of Point 4 and TPH3 resin composites. Specimens were subsequently immersed for 60 sec in either Biot&#232;ne PBF (BIO) or Listerine Total Care (LTO) mouthwashes, or water (control group; n=5/group). Biofilms were stained with fluorochromes for extracellular polymeric substances, proteins and nucleic acids before imaging with CLSM. Biofilm structural parameters calculated using ISA3D image analysis software were biovolume and mean biofilm thickness. Mixed models statistical analyses compared structural parameters between mouthwash and control groups (SAS software; &#945;=0.05). Volocity software permitted visualization of 3D distributions of overlaid biofilm components (fluorochromes). Results: Mouthwash BIO produced biofilm structures that differed significantly from the control (p&#60;0.05) on both resin composites, whereas LTO did not produce differences (p&#62;0.05) on either product. Conclusions: This methodology efficiently and successfully quantified and compared concurrent 3D distributions of three major components within S. mutans biofilms on relevant substrates, thus overcoming two challenges to simultaneous assessment of biofilm components. This method can also be used to determine the efficacy of antibacterial/antifouling agents against multiple biofilm components, as shown using mouthwashes. Furthermore, this method has broad application because it facilitates comparison of 3D structures/architecture of biofilms in a variety of disciplines.

A protocol for the concurrent quantification and comparison of three cellular and extracellular components within biofilms is presented. The methodology involves the use of confocal laser scanning microscopy, biofilm structural analysis and visualization software, and statistical analysis software.

细胞和生物膜细胞外成分的定量并发

Confocal laser scanning microscopy (CLSM) is a powerful tool for investigation of biofilms. Very few investigations have successfully quantified ...

Ratiometric Imaging of Extracellular pH in Dental Biofilms

The pH in bacterial biofilms on teeth is of central importance for dental caries, a disease with a high worldwide prevalence. Nutrients and metabolites are not distributed evenly in dental biofilms. A complex interplay of sorption to and reaction with organic matter in the biofilm reduces the diffusion paths of solutes and creates steep gradients of reactive molecules, including organic acids, across the biofilm. Quantitative fluorescent microscopic methods, such as fluorescence life time imaging or pH ratiometry, can be employed to visualize pH in different microenvironments of dental biofilms. pH ratiometry exploits a pH-dependent shift in the fluorescent emission of pH-sensitive dyes. Calculation of the emission ratio at two different wavelengths allows determining local pH in microscopic images, irrespective of the concentration of the dye. Contrary to microelectrodes the technique allows monitoring both vertical and horizontal pH gradients in real-time without mechanically disturbing the biofilm. However, care must be taken to differentiate accurately between extra- and intracellular compartments of the biofilm. Here, the ratiometric dye, seminaphthorhodafluor-4F 5-(and-6) carboxylic acid (C-SNARF-4) is employed to monitor extracellular pH in in vivo grown dental biofilms of unknown species composition. Upon exposure to glucose the dye is up-concentrated inside all bacterial cells in the biofilms; it is thus used both as a universal bacterial stain and as a marker of extracellular pH. After confocal microscopic image acquisition, the bacterial biomass is removed from all pictures using digital image analysis software, which permits to exclusively calculate extracellular pH. pH ratiometry with the ratiometric dye is well-suited to study extracellular pH in thin biofilms of up to 75 &#181;m thickness, but is limited to the pH range between 4.5 and 7.0.

A pH-sensitive ratiometric dye is used in combination with confocal laser scanning microscopy and digital image analysis to monitor extracellular pH in dental biofilms in real-time.

在口腔生物膜细胞外pH值成比例成像

The pH in bacterial biofilms on teeth is of central importance for dental caries, a disease with a high worldwide prevalence. Nutrients and metabolites ...

A New Method for Qualitative Multi-scale Analysis of Bacterial Biofilms on Filamentous Fungal Colonies Using Confocal and Electron Microscopy

Bacterial biofilms frequently form on fungal surfaces and can be involved in numerous bacterial-fungal interaction processes, such as metabolic cooperation, competition, or predation. The study of biofilms is important in many biological fields, including environmental science, food production, and medicine. However, few studies have focused on such bacterial biofilms, partially due to the difficulty of investigating them. Most of the methods for qualitative and quantitative biofilm analyses described in the literature are only suitable for biofilms forming on abiotic surfaces or on homogeneous and thin biotic surfaces, such as a monolayer of epithelial cells.
While laser scanning confocal microscopy (LSCM) is often used to analyze in situ and in vivo biofilms, this technology becomes very challenging when applied to bacterial biofilms on fungal hyphae, due to the thickness and the three dimensions of the hyphal networks. To overcome this shortcoming, we developed a protocol combining microscopy with a method to limit the accumulation of hyphal layers in fungal colonies. Using this method, we were able to investigate the development of bacterial biofilms on fungal hyphae at multiple scales using both LSCM and scanning electron microscopy (SEM). This report describes the protocol, including microorganism cultures, bacterial biofilm formation conditions, biofilm staining, and LSCM and SEM visualizations.

This protocol describes a new method to grow and qualitatively analyze bacterial biofilms on fungal hyphae by confocal and electron microscopy.

一种用于丝状真菌菌落细菌生物膜的定性多尺度分析的新方法利用共聚焦和电子显微镜

Bacterial biofilms frequently form on fungal surfaces and can be involved in numerous bacterial-fungal interaction processes, such as metabolic ...

Paraffin Embedding and Thin Sectioning of Microbial Colony Biofilms for Microscopic Analysis

Sectioning via paraffin embedding is a broadly established technique in eukaryotic systems. Here we provide a method for the fixation, embedding, and sectioning of intact microbial colony biofilms using perfused paraffin wax. To adapt this method for use on colony biofilms, we developed techniques for maintaining each sample on its growth substrate and laminating it with an agar overlayer, and added lysine to the fixative solution. These optimizations improve sample retention and preservation of micromorphological features. Samples prepared in this manner are amenable to thin sectioning and imaging by light, fluorescence, and transmission electron microscopy. We have applied this technique to colony biofilms of Pseudomonas aeruginosa, Pseudomonas synxantha, Bacillus subtilis, and Vibrio cholerae. The high level of detail visible in samples generated by this method, combined with reporter strain engineering or the use of specific dyes, can provide exciting insights into the physiology and development of microbial communities.

We describe fixation, paraffin embedding, and thin sectioning techniques for microbial colony biofilms. In prepared samples, biofilm substructure and reporter expression patterns can be visualized by microscopy.

微生物菌落生物膜的石蜡嵌入和薄切片显微分析

Sectioning via paraffin embedding is a broadly established technique in eukaryotic systems. Here we provide a method for the fixation, embedding, and ...

Production of Pseudotyped Particles to Study Highly Pathogenic Coronaviruses in a Biosafety Level 2 Setting

The protocol aims to generate coronavirus (CoV) spike (S) fusion protein pseudotyped particles with a murine leukemia virus (MLV) core and luciferase reporter, using a simple transfection procedure of the widely available HEK-293T cell line. Once formed and released from producer cells, these pseudovirions incorporate a luciferase reporter gene. Since they only contain the heterologous coronavirus spike protein on their surface, the particles behave like their native coronavirus counterparts for entry steps. As such, they are the excellent surrogates of native virions for studying viral entry into host cells. Upon successful entry and infection into target cells, the luciferase reporter gets integrated into the host cell genome and is expressed. Using a simple luciferase assay, transduced cells can be easily quantified. An important advantage of the procedure is that it can be performed in biosafety level 2 (BSL-2) facilities instead of BSL-3 facilities required for work with highly pathogenic coronaviruses such as Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus (SARS-CoV). Another benefit comes from its versatility as it can be applied to envelope proteins belonging to all three classes of viral fusion proteins, such as the class I influenza hemagglutinin (HA) and Ebola virus glycoprotein (GP), the class II Semliki forest virus E1 protein, or the class III vesicular stomatitis virus G glycoprotein. A limitation of the methodology is that it can only recapitulate virus entry steps mediated by the envelope protein being investigated. For studying other viral life cycle steps, other methods are required. Examples of the many applications these pseudotype particles can be used in include investigation of host cell susceptibility and tropism and testing the effects of virus entry inhibitors to dissect viral entry pathways used.

Here, we present a protocol to generate pseudotyped particles in a BSL-2 setting incorporating the spike protein of the highly pathogenic viruses Middle East respiratory syndrome and severe acute respiratory syndrome coronaviruses. These pseudotyped particles contain a luciferase reporter gene allowing quantification of virus entry into target host cells.

在生物安全2级环境中制备假型颗粒研究高致病性冠状病毒

The protocol aims to generate coronavirus (CoV) spike (S) fusion protein pseudotyped particles with a murine leukemia virus (MLV) core and luciferase ...

Monitoring Extracellular pH in Cross-Kingdom Biofilms using Confocal Microscopy

Cross-kingdom biofilms consisting of both fungal and bacterial cells are involved in a variety of oral diseases, such as endodontic infections, periodontitis, mucosal infections and, most notably, early childhood caries. In all of these conditions, the pH in the biofilm matrix impacts microbe-host interactions and thus the disease progression. The present protocol describes a confocal microscopy-based method to monitor pH dynamics inside cross-kingdom biofilms comprising Candida albicans and Streptococcus mutans. The pH-dependent dual-emission spectrum and the staining properties of the ratiometric probe C-SNARF-4 are exploited to determine drops in pH in extracellular areas of the biofilms. Use of pH ratiometry with the probe requires a meticulous choice of imaging parameters, a thorough calibration of the dye, and careful, threshold-based post-processing of the image data. When used correctly, the technique allows for the rapid assessment of extracellular pH in different areas of a biofilm and thus the monitoring of both horizontal and vertical pH gradients over time. While the use of confocal microscopy limits Z-profiling to thin biofilms of 75 &#181;m or less, the use of pH ratiometry is ideally suited for the noninvasive study of an important virulence factor in cross-kingdom biofilms.

The protocol describes the cultivation of cross-kingdom biofilms consisting of Candida albicans and Streptococcus mutans and presents a confocal microscopy-based method for the monitoring of extracellular pH inside these biofilms.

使用共聚焦显微镜监测跨王国生物膜中的细胞外pH值

Cross-kingdom biofilms consisting of both fungal and bacterial cells are involved in a variety of oral diseases, such as endodontic infections, ...

Clarifying and Imaging Candida albicans Biofilms

The microbial fungus Candida albicans can undergo a change from commensal colonization to virulence that is strongly correlated with its ability to switch from yeast-form growth to hyphal growth. Cells initiating this process become adherent to surfaces as well as to each other, with the resulting development of a biofilm colony. This commonly occurs not only on mucosal tissue surfaces in yeast infections, but also on medical implants such as catheters. It is well known that biofilm cells are resistant to antifungal drugs, and that cells that shed from the biofilm can lead to dangerous systemic infections. Biofilms range from heavily translucent to opaque due to refractive heterogeneity. Therefore, fungal biofilms are difficult to study by optical microscopy. To visualize internal structural, cellular, and subcellular features, we clarify fixed intact biofilms by stepwise solvent exchange to a point of optimal refractive index matching. For C. albicans biofilms, sufficient clarification is attained with methyl salicylate (n = 1.537) to enable confocal microscopy from apex to base in 600 &#181;m biofilms with little attenuation. In this visualization protocol we outline phase contrast refractometry, the growth of laboratory biofilms, fixation, staining, solvent exchange, the setup for confocal fluorescence microscopy, and representative results.

Clarifying and Imaging Candida albicans Biofilms

To view and quantify the internal features of Candida albicans biofilms, we prepare fixed intact specimens that are clarified by refractive index matching. Then, optical sectioning microscopy can be used to obtain three-dimensional image data though the full thickness of the biofilm.

澄清和成像念珠菌生物膜

The microbial fungus Candida albicans can undergo a change from commensal colonization to virulence that is strongly correlated with its ability to switch ...