This work is funded by the Young Investigator Research Program, from the Centre for Infectious Disease Research (ZINF) from the University of W&uuml;rzburg. Juan C Garcia-Betancur is a PhD fellow from the Graduate School of Life Sciences (GSLS) of the University of W&uuml;rzburg.

1. Labeling B. subtilis and Biofilm Formation Assay
<ol>
 <li>Amplify by PCR the promoter region of the gene of interest. We show as example the cloning of PtapA, the promoter of the genes responsible for the production of TasA matrix protein 26. Clone PtapA into pkm008 vector (created by the Rudner lab, Harvard Medical School. Boston, USA) (Fig. 2).</li>
 <li>Linearize the plasmids by enzymatic digestion (Enzyme recommended, XhoI).</li>
 <li>Induce natural co...

<ol>
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The fact that bacterial communities show subpopulations of cells expressing specific set of genes evidences the complexity of microbial communities 33,34. This protocol should help to determine whether the expression of any gene of interest is restricted to a particular subpopulation of specialized cells within the microbial community. Visualization of these subpopulations requires the development of new techniques, because traditional methods to monitor gene expression or microarray analysis rate the levels o...

<table border="1">
 <tbody>
 <tr>
 <td>Technique</td>
 <td>Name of the reagent</td>
 <td>Company</td>
 <td>Catalog number</td>
 </tr>
 <tr>
 <td rowspan="11">MSgg composition</td>
 <td>potassium phosphate 5mM</td>
 <td>Roth</td>
 <td>6878</td>
 </tr>
 <tr>
 <td>MOPS 100mM</td>
 <td>Sigma-Aldrich</td>
 <td>M1254</td>
 </tr>
 <tr>
 <td>Magnesium chloride 2mM</td>
 <td>Roth</td>
 <td>2189.1</td>
 </tr>
 <tr>
 <td>Calcium chloride 700&mu;M</td>
 <td>Roth</td>
 <td>A119.1</td>
 </tr>
 <tr>
 <td>Ferric chloride 50&mu;M</td>
 <td>Sigma-Aldrich</td>
 <td>157740</td>
 </tr>
 <tr>
 <td>Zinc chloride 1&mu;M</td>
 <td>Applichem</td>
 <td>A2076</td>
 </tr>
 <tr>
 <td>Thiamine 2&mu;M</td>
 <td>Sigma-Aldrich</td>
 <td>74625</td>
 </tr>
 <tr>
 <td>Glycerol 0.5%</td>
 <td>Roth</td>
 <td>7533</td>
 </tr>
 <tr>
 <td>Glutamate 0.5%</td>
 <td>Sigma-Aldrich</td>
 <td>49621</td>
 </tr>
 <tr>
 <td>Tryptophan 50&mu;g/ml</td>
 <td>Sigma-Aldrich</td>
 <td>T0254</td>
 </tr>
 <tr>
 <td>Phenylalanine 50&mu;g/ml</td>
 <td>Sigma-Aldrich</td>
 <td>P2126</td>
 </tr>
 <tr>
 <td>Cell fixation</td>
 <td>Paraformaldehyde</td>
 <td>Roth</td>
 <td>0335</td>
 </tr>
 <tr>
 <td></td>
 <td>Name of the equipment</td>
 <td>Company</td>
 <td>Catalog number</td>
 </tr>
 <tr>
 <td>Sonication</td>
 <td>Cell Sonicator</td>
 <td>Bandelin</td>
 <td>D-1000</td>
 </tr>
 <tr>
 <td>Fluorescence Microscopy</td>
 <td>Fluorescence Microscope</td>
 <td>Leica</td>
 <td>DMI6000B </td>
 </tr>
 <tr>
 <td></td>
 <td>Name of the software</td>
 <td>Company</td>
 <td>Catalog Number</td>
 </tr>
 <tr>
 <td>Fluorescence Microscopy</td>
 <td>AsaF</td>
 <td>Leica</td>
 <td></td>
 </tr>
 <tr>
 <td>Flow cytometry</td>
 <td>FCASDiva</td>
 <td>BD</td>
 <td></td>
 </tr>
 <tr>
 <td>Flow cytometry</td>
 <td>FlowJo</td>
 <td>Treestar</td>
 <td></td>
 </tr>
 </tbody>
</table>

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.

Watch this Scientific Journal Video about Single-cell Analysis of Bacillus subtilis Biofilms Using Fluorescence Microscopy and Flow Cytometry at JoVE.com

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.

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 ...

single-cell-analysis-bacillus-subtilis-biofilms-using-fluorescence

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Immunology and Infection

20.3K 조회수.  University of Würzburg. 미생물 biofilms은 일반적으로 전문의 세포 독특한 subpopulations에 의해 형성된다. 이러한 subpopulations의 단일 세포 분석은 형광 기자의 사용을 필요로합니다. 여기 몇 가지 subpopulationswithin을 시각화하고 모니터하는 프로토콜을 설명 B. subtilis 형광 현미경 및 유동세포계측법을 사용 biofilms.