The authors thank Dr. Yoav Barak from the Chemistry Faculty, Weizmann Institute, for support and advice. This study was supported by the Israel Science Foundation (grant # 913/12), and by the Minerva Foundation with funding from the Federal German Ministry for Education and Research.

Note: A detailed list of all the materials and instruments used in this protocol is shown in the Materials section.
1. Air Sampling on Filters
<ol>
	<li>Preparation of Filters
	<ol>
		<li>For high volume sampling, use 20.3 x 25.4 cm2 filters. Choose the specific type of filter that best fits the research needs, as well as the filter cut-off size, if applicable.1 Here, use quartz microfiber filters.</li>
		<li>Pre-bake filters intended for organic and biological compound...

<ol>
	<li>Lodge, J. P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Methods of Air Sampling and Analysis. , (1988).</li><li>Costa, V., 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=Characteristics+of+carbonaceous+aerosols+in+Emilia-Romagna+(Northern+Italy)+based+on+two+fall/winter+field+campaigns.">Characteristics of carbonaceous aerosols in Emilia-Romagna (Northern Italy) based on two fall/winter field campaigns.</a> Atmos. Res. , (2015).</li><li>Brent, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Development, enhancement, and evaluation of aircraft measurement techniques for national ambient air quality standard criteria pollutants [dissertation]. , (2014).</li><li>Okuda, T., Schauer, J. J., Shafer, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+methods+for+elemental+analysis+of+atmospheric+aerosols+for+evaluating+human+health+impacts+of+aerosols+in+East+Asia.">Improved methods for elemental analysis of atmospheric aerosols for evaluating human health impacts of aerosols in East Asia.</a> Atmos. Environ. 97, 552-555 (2014).</li><li>Hospodsky, D., 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=Characterizing+airborne+fungal+and+bacterial+concentrations+and+emission+rates+in+six+occupied+children's+classrooms.">Characterizing airborne fungal and bacterial concentrations and emission rates in six occupied children's classrooms.</a> Indoor air. , (2014).</li><li>Bottos, E., Woo, A., Zawar-Reza, P., Pointing, S., Cary, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Airborne+Bacterial+Populations+Above+Desert+Soils+of+the+McMurdo+Dry+Valleys,+Antarctica.">Airborne Bacterial Populations Above Desert Soils of the McMurdo Dry Valleys, Antarctica.</a> Microb. Ecol. 67, 120-128 (2014).</li><li>Ovadnevaite, J., 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=Submicron+NE+Atlantic+marine+aerosol+chemical+composition+and+abundance:+Seasonal+trends+and+air+mass+categorization.">Submicron NE Atlantic marine aerosol chemical composition and abundance: Seasonal trends and air mass categorization.</a> J. Geophys. Res. Atmos. 119, (2014).</li><li>Lodge, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ES&amp;T+Books:+Methods+of+Air+Sampling+and+Analysis,+3rd+ed.">ES&amp;T Books: Methods of Air Sampling and Analysis, 3rd ed.</a> Environ. Sci. Technol. 23, 938 (1989).</li><li>Pramod, K., Baron, P. A., Willeke, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Aerosol Measurement: Principles, Techniques, and Applications. , (2011).</li><li>Vincent, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Aerosol Sampling: Science, Standards, Instrumentation and Applications. , (2007).</li><li>Duquenne, P., Marchand, G., Duchaine, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+Endotoxins+in+Bioaerosols+at+Workplace:+A+Critical+Review+of+Literature+and+a+Standardization+Issue.">Measurement of Endotoxins in Bioaerosols at Workplace: A Critical Review of Literature and a Standardization Issue.</a> Ann. Occup. Hyg. 57, 137-172 (2013).</li><li>Okuda, T., Schauer, J. J., Shafer, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+methods+for+elemental+analysis+of+atmospheric+aerosols+for+evaluating+human+health+impacts+of+aerosols+in+East+Asia.">Improved methods for elemental analysis of atmospheric aerosols for evaluating human health impacts of aerosols in East Asia.</a> Atmos. Environ. 97, 552-555 (2014).</li><li>Lewtas, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Air+pollution+combustion+emissions:+Characterization+of+causative+agents+and+mechanisms+associated+with+cancer,+reproductive,+and+cardiovascular+effects.">Air pollution combustion emissions: Characterization of causative agents and mechanisms associated with cancer, reproductive, and cardiovascular effects.</a> Mutat. Res.-Rev. Mutat. 636, 95-133 (2007).</li><li>Lang-Yona, N., Lehahn, Y., Herut, B., Burshtein, N., Rudich, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Marine+aerosol+as+a+possible+source+for+endotoxins+in+coastal+areas.">Marine aerosol as a possible source for endotoxins in coastal areas.</a> Sci. Total. Environ. 499, 311-318 (2014).</li><li>Levin, J., Bang, F. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clottable+protein+in+Limulus:+its+localization+and+kinetics+of+its+coagulation+by+endotoxin.">Clottable protein in Limulus: its localization and kinetics of its coagulation by endotoxin.</a> Thromb. Diath. Haemorrh. 19, 186-197 (1968).</li><li>Heid, C. A., Stevens, J., Livak, K. J., Williams, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real+time+quantitative+PCR.">Real time quantitative PCR.</a> Genome Res. 6, 986-994 (1996).</li><li>O'Dowd, C. D., de Leeuw, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Marine+aerosol+production:+a+review+of+the+current+knowledge.">Marine aerosol production: a review of the current knowledge.</a> Phil. Trans. R. Soc. A. 365, 1753-1774 (2007).</li><li>O'Dowd, C. D., 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=Biogenically+driven+organic+contribution+to+marine+aerosol.">Biogenically driven organic contribution to marine aerosol.</a> Nature. 431, 676-680 (2004).</li><li>Yang, R., Paparini, A., Monis, P., Ryan, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+next-generation+droplet+digital+PCR+(ddPCR)+with+quantitative+PCR+(qPCR)+for+enumeration+of+Cryptosporidium+oocysts+in+faecal+samples.">Comparison of next-generation droplet digital PCR (ddPCR) with quantitative PCR (qPCR) for enumeration of Cryptosporidium oocysts in faecal samples.</a> Int. J. Parasitol. 44, 1105-1113 (2014).</li><li>Stetzenbach, L. D., Buttner, M. P., Cruz, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+and+enumeration+of+airborne+biocontaminants.">Detection and enumeration of airborne biocontaminants.</a> Curr. Opin. Biotechnol. 15, 170-174 (2004).</li><li>Dannemiller, K. C., Gent, J. F., Leaderer, B. P., Peccia, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+housing+characteristics+on+bacterial+and+fungal+communities+in+homes+of+asthmatic+children.">Influence of housing characteristics on bacterial and fungal communities in homes of asthmatic children.</a> Indoor air. , (2015).</li><li>Yamamoto, N., Hospodsky, D., Dannemiller, K. C., Nazaroff, W. W., Peccia, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Indoor+emissions+as+a+primary+source+of+airborne+allergenic+fungal+particles+in+classrooms.">Indoor emissions as a primary source of airborne allergenic fungal particles in classrooms.</a> Environ. Sci. Technol. 49, 5098-5106 (2015).</li><li>Yamamoto, N., 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=Particle-size+distributions+and+seasonal+diversity+of+allergenic+and+pathogenic+fungi+in+outdoor+air.">Particle-size distributions and seasonal diversity of allergenic and pathogenic fungi in outdoor air.</a> ISME J. 6, 1801-1811 (2012).</li><li>Karottki, D. G., 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=Cardiovascular+and+lung+function+in+relation+to+outdoor+and+indoor+exposure+to+fine+and+ultrafine+particulate+matter+in+middle-aged+subjects.">Cardiovascular and lung function in relation to outdoor and indoor exposure to fine and ultrafine particulate matter in middle-aged subjects.</a> Environ Int. 73, 372-381 (2014).</li><li>Guy, D., Hodges, N., Hanlon, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotoxins+and+Depyrogenation.">Endotoxins and Depyrogenation.</a> Industrial Pharmaceutical Microbiology: Standards and Controls. , 12.1-12.15 (2003).</li><li>Thorne, P. S., Bartlett, K. H., Phipps, J., Kulhankova, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+Five+Extraction+Protocols+for+Quantification+of+Endotoxin+in+Metalworking+Fluid+Aerosol.">Evaluation of Five Extraction Protocols for Quantification of Endotoxin in Metalworking Fluid Aerosol.</a> Ann. Occup. Hyg. 47, 31-36 (2003).</li><li>Thornton, B., Basu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+PCR+(qPCR)+primer+design+using+free+online+software.">Real-time PCR (qPCR) primer design using free online software.</a> Biochem. Mol. Biol. Educ. 39, 145-154 (2011).</li><li>Madigan, M. T., Clark, D. P., Stahl, D., Martinko, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Brock Biology of Microorganisms. , (2011).</li><li>Watson, J. G., Chow, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Aerosol Measurement: Principles and Techniques. , 591-613 (2011).</li><li>Mueller-Anneling, L., Avol, E., Peters, J. M., Thorne, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ambient+endotoxin+concentrations+in+PM10+from+Southern+California.">Ambient endotoxin concentrations in PM10 from Southern California.</a> Environ. Health Perspect. 112, 583-588 (2004).</li><li>Hospodsky, D., Yamamoto, N., Peccia, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accuracy,+Precision,+and+Method+Detection+Limits+of+Quantitative+PCR+for+Airborne+Bacteria+and+Fungi.">Accuracy, Precision, and Method Detection Limits of Quantitative PCR for Airborne Bacteria and Fungi.</a> Appl. Environ. Microbiol. 76, 7004-7012 (2010).</li><li>Kutyavin, I. V., 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=3&#8242;-Minor+groove+binder-DNA+probes+increase+sequence+specificity+at+PCR+extension+temperatures.">3&#8242;-Minor groove binder-DNA probes increase sequence specificity at PCR extension temperatures.</a> Nucleic Acids Res. 28, 655-661 (2000).</li><li>Brankatschk, R., Bodenhausen, N., Zeyer, J., B&#252;rgmann, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple+absolute+quantification+method+correcting+for+quantitative+PCR+efficiency+variations+for+microbial+community+samples.">Simple absolute quantification method correcting for quantitative PCR efficiency variations for microbial community samples.</a> Appl. Environ. Microbiol. 78, 4481-4489 (2012).</li><li>Strober, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Appendix+3B,+Trypan+Blue+Exclusion+Test+of+Cell+Viability.">Appendix 3B, Trypan Blue Exclusion Test of Cell Viability.</a> Current Protocols in Immunology. , (2001).</li><li>Hollander, A., Heederik, D., Versloot, P., Douwes, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+and+enhancement+in+the+analysis+of+airborne+endotoxin+levels+in+various+occupational+environments.">Inhibition and enhancement in the analysis of airborne endotoxin levels in various occupational environments.</a> Am Ind Hyg Assoc J. 54, 647-653 (1993).</li><li>Kennedy, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> PCR troubleshooting and optimization : the essential guide. , (2011).</li><li>Joiner, T. 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This work describes extraction and detection methods for quantifying both endotoxins and DNA present in aerosol samples collected on filters. The methods require accurate routines and can be performed easily as long as the experimentalist adheres to a few essential and important points discussed here.
For the endotoxin detection step, note that the lysate solution is quite viscous and tends to produce bubbles upon pipetting. It is difficult to remove thee bubbles, and they lead to changes in t...

Air sampling on filters is a basic tool in atmospheric aerosols research.1 The sampled filters are the starting point for various chemical, physical, and biological characterizations of the collected ambient particles.2-11 The advantage of this approach is that various analyses can be performed off-line on the same sample. Compiling the data from all the different analyses enables the researcher to obtain a good understanding of the characteristics of the collected particles and aids in solving complex questions in the atmospheric sciences.12,13 For example, marine and inland air-samples taken during the same period can be compared with respect to the sampled particle toxicity and biological composition.14 For this study, lipopolysaccharides (LPS), components on gram-negative bacterial cell-walls, also known as endotoxins, were extracted from filters sampled on-shore and at an inland site, and were evaluated using the limulus amebocyte lysate (LAL) test. In parallel, a genomic evaluation of the bacterial content (total bacteria, gram negative, and cyanobacteria) was performed on the same sample using the quantitative polymerase chain reaction (q-PCR). The LAL test is based on measurements of turbidity formed following the addition of an aqueous extract of amebocytes from the horseshoe crab, Limulus polyphemus, to an aqueous solution containing the endotoxins. The higher the endotoxin concentration in the sample, the faster turbidity develops.15 The q-PCR analysis is based on a fluorescence signal emitted as a specific DNA fragment is amplified.16 By real time monitoring of the signal during the exponential phase of the PCR reaction and calibrating with a standard curve, the initial DNA amount can be quantified. The combination of these two analyses together with others, as detailed elsewhere,14 can provide a good estimation of the levels of endotoxin and the amount of the source bacteria in the samples.
The purpose of the method presented here is to obtain a highly accurate and reliable analysis of the endotoxin and DNA content of bio-aerosols extracted from filters. While methods for sampling the physical and inorganic chemical characteristics of aerosols are well known and, more recently, methods have been developed to investigate its organic matter component,17 there has been scant research on the biological component of aerosols.18 The rationale for the current method is to address this gap by presenting in detail a robust method for extracting, analyzing, and identifying the biological fraction of airborne aerosols.14
The method detailed here is expected to find wide-spread use in biological indoor and outdoor aerosol research projects involving filter analysis.20-24

<table border="0" cellpadding="0" cellspacing="0" width="631">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:187px;">Filter sampling</td>
			<td style="width:123px;"></td>
			<td style="width:103px;"></td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">HiVol 3000 - High Air Volume Sampler</td>
			<td style="width:123px;">Ecotech</td>
			<td style="width:103px;"></td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:187px;">Quartz Microfiber Filters</td>
			<td style="width:123px;">Whatman</td>
			<td style="width:103px;">1851-865</td>
			<td style="width:220px;">203mm X 254mm</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">ELF - Laboratory Chamber Furnaces</td>
			<td style="width:123px;">Carbolite</td>
			<td style="width:103px;">ELF 11series</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:187px;">Aluminum foil</td>
			<td style="width:123px;">Opal</td>
			<td style="width:103px;"></td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:187px;">Name</td>
			<td style="width:123px;">Company</td>
			<td style="width:103px;">Catalog Number</td>
			<td style="width:220px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:187px;">Endotoxin</td>
			<td style="width:123px;"></td>
			<td style="width:103px;"></td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:187px;">Ethanol</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:103px;">16368&#160;</td>
			<td style="width:220px;">Laboratory Reagent, 96%</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">Airstream Class II Biological Safety Cabinet AC-4E1</td>
			<td style="width:123px;">ESCO</td>
			<td style="width:103px;">10011712</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">Pyrotell -T</td>
			<td style="width:123px;">Associates of Cape Cod, Inc.</td>
			<td style="width:103px;">T0051</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">Control Standard Endotoxin</td>
			<td style="width:123px;">Associates of Cape Cod, Inc.</td>
			<td style="width:103px;">E0005-1</td>
			<td style="width:220px;">Escherichia coli&#160;O113:H10, 0.5 &#181;g/vial 1 Pack</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">LAL Reagent Water</td>
			<td style="width:123px;">Associates of Cape Cod, Inc.</td>
			<td style="width:103px;">W0051</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">10 mL sterile syringe with Luer-Lok Tip</td>
			<td style="width:123px;">Becton-Dickinson &#38; Co.</td>
			<td style="width:103px;">309605</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">BD Precisionglide syringe needle</td>
			<td style="width:123px;">Becton-Dickinson &#38; Co.</td>
			<td style="width:103px;">305129</td>
			<td style="width:220px;">Sterile&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:187px;">Parafilm-M sealing tape</td>
			<td style="width:123px;">Parafilm</td>
			<td style="width:103px;">P7543</td>
			<td style="width:220px;">Sigma catalog number</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:187px;">Microtubes</td>
			<td style="width:123px;">Axigen</td>
			<td style="width:103px;">MCT-200-C</td>
			<td style="width:220px;">2ml, pyrogen free</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">1.12 cm diameter Cork Borer</td>
			<td style="width:123px;">Boekel Scientific</td>
			<td style="width:103px;">1601 BD Series - Steel</td>
			<td style="width:220px;">Part of a cork borer set containing borers with various diameters.&#160;</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">50 mm Petri Dish</td>
			<td style="width:123px;">Miniplast Ein-Shemer</td>
			<td style="width:103px;">72050-01</td>
			<td style="width:220px;">Aseptic</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">Vortex Genie 2&#160;</td>
			<td style="width:123px;">Scientific Industries, inc.</td>
			<td style="width:103px;">SI-0297</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:187px;">Microcentrifuge 5415 D</td>
			<td style="width:123px;">Eppendorf</td>
			<td style="width:103px;">22621408</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="51">
			<td height="51" style="height:51px;width:187px;">TC MicroWell 96 F SI w/lid</td>
			<td style="width:123px;">Nunc</td>
			<td style="width:103px;">167008</td>
			<td style="width:220px;">Flat bottom wells (with lid (individually wrapped)), sterile, pyrogen free</td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:187px;">Synergy HT Multi-Detection Microplate Reader</td>
			<td style="width:123px;">Biotek</td>
			<td style="width:103px;">7091000</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:187px;">Name</td>
			<td style="width:123px;">Company</td>
			<td style="width:103px;">Catalog Number</td>
			<td style="width:220px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:187px;">DNA</td>
			<td style="width:123px;"></td>
			<td style="width:103px;"></td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:187px;">DNA away</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:103px;">7010</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="51">
			<td height="51" style="height:51px;width:187px;">Standard DNA of the microbial species of interest</td>
			<td style="width:123px;">ATCC or other culture collection</td>
			<td style="width:103px;"></td>
			<td style="width:220px;">Either the appropriate microbial strain for DNA extraction or the extracted DNA</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:187px;">Neubauer-improved</td>
			<td style="width:123px;">Marienfeld</td>
			<td style="width:103px;">640030</td>
			<td style="width:220px;">hemocytometer</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">TE buffer, Low EDTA</td>
			<td style="width:123px;">Life Technologies</td>
			<td style="width:103px;">12090-015</td>
			<td style="width:220px;">10 mM Tris-HCl (pH 8.0)&#160;0.1 mM EDTA&#160;</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">Nuclease-free PCR-grade water&#160;</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:103px;">3315959001</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">PCR primers</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:103px;"></td>
			<td style="width:220px;">Targets the microbial species of interest</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">Dual-Labeled Probes</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:103px;"></td>
			<td style="width:220px;">Targets the microbial species of interest</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:187px;">Screw cap tubes</td>
			<td style="width:123px;">Axigen</td>
			<td style="width:103px;">ST-200-SS</td>
			<td>2 mL&#160;</td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">PowerSoil DNA extraction kit&#160;</td>
			<td style="width:123px;">Mo Bio Laboratories</td>
			<td style="width:103px;">12888-100</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">Glass beads, acid-washed 425-600 Microns</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:103px;">G8772-100G</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">Glass beads, acid-washed &#60;106 microns</td>
			<td style="width:123px;">Sigma Aldrich</td>
			<td style="width:103px;">G4649-100G</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;">PowerSoil Solution C1</td>
			<td style="width:123px;">Mo Bio Laboratories</td>
			<td style="width:103px;">12888-100-1</td>
			<td style="width:220px;">Cell lysis buffer , Power soil Kit</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:187px;">Magic Touch ice bucket</td>
			<td style="width:123px;">Bel-Art</td>
			<td style="width:103px;">18848-4001</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:187px;">Mini-Beadbeater-16</td>
			<td style="width:123px;">BioSpec</td>
			<td style="width:103px;">607EUR</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">StepOnePlus Real-Time PCR System</td>
			<td style="width:123px;">Applied Biosystems</td>
			<td style="width:103px;">4376600</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">Fast SYBR Green Master Mix</td>
			<td style="width:123px;">Applied Biosystems</td>
			<td style="width:103px;">4385612</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">TaqMan Gene Expression Master Mix</td>
			<td style="width:123px;">Applied Biosystems</td>
			<td style="width:103px;">4370048</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="51">
			<td height="51" style="height:51px;width:187px;">MicroAmp Fast Optical 96-Well Reaction Plate with Barcode, 0.1 mL</td>
			<td style="width:123px;">Applied Biosystems</td>
			<td style="width:103px;">4346906</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">MicroAmp Splash-Free 96-Well Base</td>
			<td style="width:123px;">Applied Biosystems</td>
			<td style="width:103px;">4312063</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:187px;">MicroAmp Optical Adhesive Film</td>
			<td style="width:123px;">Applied Biosystems</td>
			<td style="width:103px;">4311971</td>
			<td style="width:220px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:187px;">Centrifuge 5810 R</td>
			<td style="width:123px;">Eppendorf</td>
			<td style="width:103px;">5811 000.010</td>
			<td style="width:220px;">Rotor A-4-62 with MTP buckets&#160;</td>
		</tr>
	</tbody>
</table>

air-sampled filter analysis for endotoxins and dna content

Outdoor aerosol research commonly uses particulate matter sampled on filters. This procedure enables various characterizations of the collected particles to be performed in parallel. The purpose of the method presented here is to obtain a highly accurate and reliable analysis of the endotoxin and DNA content of bio-aerosols extracted from filters. The extraction of high molecular weight organic molecules, such as lipopolysaccharides, from sampled filters involves shaking the sample in a pyrogen-free water-based medium. The subsequent analysis is based on an enzymatic reaction that can be detected using a turbidimetric measurement. As a result of the high organic content on the sampled filters, the extraction of DNA from the samples is performed using a commercial DNA extraction kit that was originally designed for soils and modified to improve the DNA yield. The detection and quantification of specific microbial species using quantitative polymerase chain reaction (q-PCR) analysis are described and compared with other available methods.

It is common to study atmospheric aerosols using &#34;off-line&#34; analyses of sampled filters (see Figure 2).32 Chemical analyses of the sampled matter include organic (e.g. protein, hydrocarbon molecules, saccharides) and inorganic (e.g. metals, salts) content. Biological analyses include viable and non-viable microorganism content, species identification using a DNA approach or microscopy, as well as DNA-based quantification.
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Watch this Scientific Journal Video about Air-sampled Filter Analysis for Endotoxins and DNA Content at JoVE.com

Air-sampled Filter Analysis for Endotoxins and DNA Content

Two complementary analyses of atmospheric biological particles from air sampled filters are described herein: the extraction and detection of endotoxin, and of DNA.

Outdoor aerosol research commonly uses particulate matter sampled on filters. This procedure enables various characterizations of the collected particles ...

The overall goal of this procedure is to describe how to accurately analyze endotoxin and DNA content of extracted airborne particles sampled on filters. This method can help answer key questions in indoor and outdoor biological aerosol research, such as understanding health reasons. Demonstrating the filter sampling procedure will be Yinon Mazar, a graduate student from my laboratory.For high volume sampling, use filters made of quartz fiber. Or choose the specific type of filter as well as a filter cutoff size, that best fits the research needs. Prebake the filters intended for organic and biological compound sampling by first wrapping them individually in aluminum foil.And then baking them in a laboratory furnace at 450 degrees Celsius for at least five hours. This will destroy any preexisting organic residues. Store the baked filters at 20 degrees Celsius until they are to be used for sampling.Next, clean and disinfect the high volume sampler such as the one described in the accompanying text protocol. Then, place the prebaked filter into the filter cassette and run the sampler in accordance with manufacturer's instructions to collect an appropriate sample. In a class two biosafety cabinet, cut 22 circular pieces of clean, prebaked filter material using a clean 1.12 centimeter diameter cork borer.Use these pieces to prepare a range of endotoxin spiked filters to be used as controls. Next, cut the filters containing the collected sample using a clean 1.12 centimeter diameter cork borer and place each sample into its own pyrogen free two millileter tube. Also, transfer the dried endotoxin spiked filters into separate pyrogen free two millileter tubes.Add one milliliter of pyrogen free water to each tube. And shake them for 60 minutes at room temperature using a laboratory shaker. Next, centrifuge the sample tubes in a microcentrifuge at 375 times G for 10 minutes.Then, transfer the supernatant which contains the endotoxins into a new pyrogen free two milliliter tube. Prepare a pyrogen free 96 well flat bottom microplate with a lid for the endotoxin test. By first laying out the sample locations.Next, turn on the microplate reader and program it for a kinetic reaction at 37 degrees Celsius with shaking every five minutes. Followed by measurements at 405 nanometers. Repeat the five minute shake and the plate reading 18 times.Load the samples into the acate by placing 50 microliters of the standard endotoxin solutions previously used to spike the filters into rows A1 through A10 and B1 through B10. Place the blanks into A11, A12, B11 and B12. Next, add the supernatant from the spun spiked filter extract and its blanks into rows C and D.Then, add the supernatants from the experimental samples and blanks into the remaining wells as needed.To activate the test, quickly add 50 microliters of the limulus amebocyte glycate solution to each well. Gently shake the plate horizontally. Before lifting it into the plate reader and starting the experimental run.Once finished, remove the plate from the plate reader. Determine the endotoxin level in each sample using the standard curve, and also calculate the efficiency with which the endotoxins are extracted from the sample filters. First, prepare the DNA spiked filters as described in the accompanying text protocol.For each filter sample, prepare a mixture of acid washed glass beads to 0.5 milliliter sterile tubes at 0.1 grams of beads that have a diameter of 425 to 600 micrometers and 0.3 grams of beads that have a diameter of less than or equal to 106 micrometers. Next, cut three circular pieces from randomly selected locations on each filter sample using a disinfected 1.12 centimeter diameter cork borer. Place the filter samples into individual screw-top two milliliter tubes.Then, add the glass bead mixture to each tube along with 60 microliters of the cell lysis buffer supplied with the DNA extraction kit. Close the tubes and place the samples into the bead beater. Use the bead beater to disrupt the filtered cells mechanically for one minute and then cool the samples by placing them on ice for an additional minute.Repeat this cycle fives times. Proceed to follow the kit supplier's protocol and extract the DNA from the lysed cells. After elution, reload the eluted sample through the extraction column a second time to improve the DNA yield.Switch on the quantitative PCR instrument in advance to allow it time to warm up. In a new program file, insert the details for the quantitative PCR run in the instrument operating software. Next, disinfect the work surface with surface DNA decontaminant and work only with sterile tubes, tips and reagents.Also, place a bucket of ice next to the working bench and place the tac polemoraris mix into the bucket. Prepare the quantitative PCR reaction mix as described in table four of the accompanying text protocol. And store the reaction mix in the dark and on ice until use.Next, place a clean microplate into a plate holder to prevent it from touching the working surface and to keep it clean. Add one microliter of standard DNA, sample DNA or nuclease-free water, inside the wells of the quantitative PCR microplate in triplicate. Then, add nine microliters of the master reaction mix into each reaction well.When finished, cover the plate with optical adhesive film and seal it tightly on all sides. Spin down the plate in a centrifuge equipped with plate buckets for one minute at 1000 times G.Before placing it in the thermocycler. Finally, activate and run the prepared quantitative PCR program.During the endotoxin extraction, filter samples are spun on a centrifuge to extract the endotoxin from the filter. Different centrifugation speeds result in various extraction efficiencies. Especially at higher endotoxin concentrations.A preliminary test for extraction efficiency should be conducted for the specific filter chosen and protocol performed. Higher extraction efficiencies are obtained from spiking clean filters compared with sampled quartz filters and both of these efficiencies are lower than that achieved via direct detection of the standard solution. Once mastered, the endotoxin analysis can be done in three and a half hours if it is performed properly.Following this procedure, other methods like DNA sequencing can be performed in order to answer additional questions regarding the transport of organisms in the atmosphere. After watching this video, you should have a good understanding of how to efficiently extract endotoxins and DNA from air sample filters and analyze them accurately.

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9.6K vistas.  Weizmann Institute of Science. The overall goal of this procedure is to describe how to accurately analyze endotoxin and DNA content of extracted airborne particles sampled on filters. This method can help answer key questions in indoor and outdoor biological aerosol research, such as understanding health reasons. Demonstrating the filter sampling procedure will be Yinon Mazar, a graduate student from my laboratory.For high volume sampling, use filters made of quartz fiber. Or choose the specific type of filter as w...