Name: physical isolation of endospores from environmental samples by targeted lysis of vegetative cells
Uploaded: 2016-01-21T13:00:00
Description: Watch this Scientific Journal Video about Physical Isolation of Endospores from Environmental Samples by Targeted Lysis of Vegetative Cells at JoVE.com

The authors acknowledge the Swiss National Science Foundation for Grant No. 31003A-132358/1, 31003A_152972 and No. 151948, and Fundation Pierre Mercier pour la Science.

1. Preparation of Chemicals and Equipment&#160;
<ol>
	<li>Make 500 ml of a 1% sodium hexametaphosphate (SHMP) (NaPO3)n solution and sterilize by autoclaving.</li>
	<li>Sterilize nitrocellulose (NC) filters (pore size 0.22 &#181;m, diameter 47 mm) by autoclaving in closed glass Petri dishes.</li>
	<li>Sterilize NC filters (pore size 0.22 &#181;m, diameter 25 mm) by autoclaving in closed glass Petri dishes.</li>
	<li>Weigh and note the empty weight of sterile 50 ml tubes (with cap on) (one tube per ...

<ol>
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N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+archaea+and+bacteria+dominate+stable+microbial+communities+in+North+America's+Largest+Hot+Spring.">Novel archaea and bacteria dominate stable microbial communities in North America's Largest Hot Spring.</a> Microb Ecol. 56 (2), 292-305 (2008).</li><li>Hugenholtz, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+prokaryotic+diversity+in+the+genomic+era.">Exploring prokaryotic diversity in the genomic era.</a> Genome Biol. 3 (2), (2002).</li><li>Onyenwoke, R. U., Brill, J. 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R., Gray, T. R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Populations+of+spore-forming+bacteria+in+an+acid+forest+soil,+with+special+reference+to+Bacillus+subtilis.">Populations of spore-forming bacteria in an acid forest soil, with special reference to Bacillus subtilis.</a> J General Microbiol. 81 (1), 183-190 (1974).</li><li>Brandes Ammann, A., Kolle, L., Brandl, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+bacterial+endospores+in+soil+by+terbium+fluorescence.">Detection of bacterial endospores in soil by terbium fluorescence.</a> Int J Microbiol. , 435281 (2011).</li><li>Fichtel, J., Koster, J., Rullkotter, J., Saas, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+variations+in+endospore+numbers+within+tidal+flat+sediments+revealed+by+quantification+of+dipicolinic+acid.">High variations in endospore numbers within tidal flat sediments revealed by quantification of dipicolinic acid.</a> Geomicrobiol J. 25 (7-8), (2008).</li><li>Cronin, U. P., Wilkinson, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+potential+of+flow+cytometry+in+the+study+of+Bacillus+cereus.">The potential of flow cytometry in the study of Bacillus cereus.</a> J Appl Microbiol. 108 (1), 1-16 (2010).</li><li>de Rezende, J. R., 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=Dispersal+of+thermophilic+Desulfotomaculum+endospores+into+Baltic+Sea+sediments+over+thousands+of+years.">Dispersal of thermophilic Desulfotomaculum endospores into Baltic Sea sediments over thousands of years.</a> ISME J. 7 (1), 72-84 (2013).</li><li>Hubert, C., 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=Thermophilic+anaerobes+in+Arctic+marine+sediments+induced+to+mineralize+complex+organic+matter+at+high+temperature.">Thermophilic anaerobes in Arctic marine sediments induced to mineralize complex organic matter at high temperature.</a> Environ Microbiol. 12 (4), 1089-1104 (2010).</li><li>Garbeva, P., van Veen, J. A., van Elsas, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Predominant+Bacillus+spp.+in+agricultural+soil+under+different+management+regimes+detected+via+PCR-DGGE.">Predominant Bacillus spp. in agricultural soil under different management regimes detected via PCR-DGGE.</a> Microb Ecol. 45 (3), 302-316 (2003).</li><li>Brill, J. A., Wiegel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+between+spore-forming+and+asporogenic+bacteria+using+a+PCR+and+southern+hybridization+based+method.">Differentiation between spore-forming and asporogenic bacteria using a PCR and southern hybridization based method.</a> J Microbiol Methods. 31 (1-2), 29-36 (1997).</li><li>Rueckert, A., Ronimus, R. S., Morgan, H. W. <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+a+real-time+PCR+assay+targeting+the+sporulation+gene,+spo0A.,+for+the+enumeration+of+thermophilic+bacilli+in+milk+powder.">Development of a real-time PCR assay targeting the sporulation gene, spo0A., for the enumeration of thermophilic bacilli in milk powder.</a> Food Microbiol. 23 (3), 220-230 (2006).</li><li>Bueche, M., 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=Quantification+of+endospore-forming+firmicutes+by+quantitative+PCR+with+the+functional+gene+spo0A.">Quantification of endospore-forming firmicutes by quantitative PCR with the functional gene spo0A.</a> Appl Environ Microbiol. 79 (17), 5302-5312 (2013).</li><li>Wunderlin, T., Junier, T., Roussel-Delif, L., Jeanneret, N., Junier, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endospore-enriched+sequencing+approach+reveals+unprecedented+diversity+of+Firmicutes+in+sediments.">Endospore-enriched sequencing approach reveals unprecedented diversity of Firmicutes in sediments.</a> Environ Microbiol Rep. 6 (6), 631-639 (2014).</li><li>Nicholson, W. 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The resistance of endospores to external aggressive physicochemical factors (e.g., temperature or detergents) was used to devise a method to separate bacterial endospores from vegetative cells in environmental samples. This is the first comprehensive method to isolate endospores from environmental samples in a non-destructive manner. Previous methods to quantify, detect or analyze endospores in samples were based on the measurement of specific proxies for endospores such as dipicolinic acid or specific marker ge...

The goal of this work is to provide a protocol for the separation of bacterial endospores from vegetative bacterial cells in environmental samples. The formation of bacterial endospores is a survival strategy, usually triggered by starvation, found in a number of bacterial groups belonging to the phylum Firmicutes1. Endospore-forming bacteria are well studied, mainly because a number of strains are pathogens and hence of medical importance (e.g., Bacillus anthracis or Clostridium difficile). Environmental strains of endospore-forming bacteria have been isolated from virtually every environment (soil, water, sediment, air, ice, human gut, animals gut, and more)1-3. Therefore, Firmicutes are the second most abundant phylum in culture collections4.
Because of their hardy outer cortex and protective core proteins, endospores can survive extreme environmental conditions ranging from desiccation to high radiation, extreme temperatures and harmful chemicals5. This remarkable resistance makes it a challenge to extract DNA from endospores6-8. This likely explains why they have been overlooked in environmental sequencing studies9,10. Other methods, such as targeting of endospores in environmental samples by fluorescent antibodies11, quantification of dipicolinic acid (DPA) in soil12 and sediment13, flow cytometry14 or pasteurization and subsequent cultivation15,16 have been used to retrieve or quantify endospores in environmental samples. In recent years, optimized DNA extraction methods as well as specific molecular primers to target endospore-specific gene sequences have been developed10,17-20. This has helped to reveal more biodiversity among this group of bacteria21 and has also led to applications in industry and medicine for the detection of endospores, for example in milk powder19.
The protocol presented here is based on the difference in resistance to harmful physicochemical conditions (such as heat and detergents) of bacterial endospores relative to vegetative cells. To destroy vegetative cells in a sample, we consecutively apply heat, lysozyme and low concentrations of detergents. The time and strength of these treatments have been optimized so as not to destroy spores, but to lyse all vegetative cells. Some cells in an environmental cell pool are more resistant than others, so in order to increase the probability of destroying all vegetative cells, we apply three different treatments. The advantage and novelty of this method is that the endospores after the treatment are still intact and can be used for further downstream analyses. These include DNA extraction, quantitative PCR (qPCR) and amplicon or metagenomic sequencing (targeting specifically the group of endospores and thus reducing diversity, while increasing coverage). The endospores could also be used for downstream cultivation or quantification by fluorescence microscopy, flow cytometry, or detection of DPA. An important feature of this method is that by comparing an untreated sample with a treated sample, one can deduce the quantity and diversity of endospores in an environmental sample in addition to the component corresponding to vegetative cells.

<table border="0" cellpadding="0" cellspacing="0" width="596">
	<tbody>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Whatman nitrocellulose membrane filters, 0,2 um pore size, 47 mm diameter</td>
			<td style="width:95px;">Sigma-Aldrich</td>
			<td colspan="2" style="width:285px;">WHA7182004 Aldrich&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Tris(hydroxymethyl)aminomethane</td>
			<td style="width:95px;">Sigma-Aldrich</td>
			<td>252859 Sigma-Aldrich</td>
			<td>CAS 77-86-1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">EDTA</td>
			<td>Sigma-Aldrich</td>
			<td>E9884 Sigma-Aldrich</td>
			<td>CAS&#160; 60-00-4&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Lysozyme from chicken egg white</td>
			<td>Sigma-Aldrich</td>
			<td>62971 Fluka</td>
			<td>powder, CAS&#160; 12650-88-3&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Ultra-Turrax homogenizer T18 basic</td>
			<td style="width:95px;">IKA</td>
			<td>3720000</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Glass filter holders for 47 mm membranes, pyrex glass</td>
			<td style="width:95px;">EMD Millipore</td>
			<td>XX10 047 00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Chemical duty vacuum pump</td>
			<td style="width:95px;">Millipore</td>
			<td style="width:119px;">WP6122050</td>
			<td>220 V/50 Hz</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Manifold sampling filtration for 25 mm membranes</td>
			<td style="width:95px;">Millipore</td>
			<td>1225 Sampling Manifold</td>
			<td>polypropylene</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dnase</td>
			<td style="width:95px;">New England Biolabs</td>
			<td>M0303S</td>
			<td>Rnase free</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaOH</td>
			<td>Sigma-Aldrich</td>
			<td>S5881 Sigma-Aldrich</td>
			<td>CAS&#160; 1310-73-2&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium dodecyl sulfphate (SDS)</td>
			<td>Sigma-Aldrich</td>
			<td>L3771 Sigma&#160;</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Whatman nitrocellulose membrane filters, 0,2 um pore size, 25 mm diameter</td>
			<td>Sigma-Aldrich</td>
			<td colspan="2">WHA7182002 Aldrich</td>
		</tr>
	</tbody>
</table>

physical isolation of endospores from environmental samples by targeted lysis of vegetative cells

Endospore formation is a survival strategy found among some bacteria from the phylum Firmicutes. During endospore formation, these bacteria enter a morpho-physiological resting state that enhances survival under adverse environmental conditions. Even though endospore-forming Firmicutes are one of the most frequently enriched and isolated bacterial groups in culturing studies, they are often absent from diversity studies based on molecular methods. The resistance of the spore core is considered one of the factors limiting the recovery of DNA from endospores. We developed a method that takes advantage of the higher resistance of endospores to separate them from other cells in a complex microbial community using physical, enzymatic and chemical lysis methods. The endospore-only preparation thus obtained can be used for re-culturing or to perform downstream analysis such as tailored DNA extraction optimized for endospores and subsequent DNA sequencing. This method, applied to sediment samples, has allowed the enrichment of endospores and after sequencing, has revealed a large diversity of endospore-formers in freshwater lake sediments. We expect that the application of this method to other samples will yield a similar outcome.

The results presented here have been published earlier10,21. Please refer to those articles for the environmental interpretation and discussion of the data.
The overall procedure is summarized in Figure 1 and corresponds to three main steps: first, the separation of biomass from sediment or any other environmental matrix; second, the destruction of vegetative cells; and third, the downstream analysis of the separated endospores. Downstream analysis could consist, fo...

Watch this Scientific Journal Video about Physical Isolation of Endospores from Environmental Samples by Targeted Lysis of Vegetative Cells at JoVE.com

Physical Isolation of Endospores from Environmental Samples by Targeted Lysis of Vegetative Cells

A method to single out bacterial endospores from complex microbial communities was developed to perform tailored culture or molecular studies of this group of bacteria.

Endospore formation is a survival strategy found among some bacteria from the phylum Firmicutes. During endospore formation, these bacteria enter a ...

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