Name: collection and extraction of occupational air samples for analysis of fungal dna
Uploaded: 2018-05-02T13:00:00
Description: Watch this Scientific Journal Video about Collection and Extraction of Occupational Air Samples for Analysis of Fungal DNA at JoVE.com

Este trabajo fue apoyado en parte por un acuerdo interinstitucional entre NIOSH y de NIEHS (AES12007001-1-0-6).

1. preparación de la muestra de aerosol NIOSH
Nota: La muestra de aerosol NIOSH es un dechado de aerosol de ciclón de dos etapas que recoge bioaerosoles utilizando dos tubos de muestreo y un filtro de politetrafluoroetileno (PTFE).
<ol><li>Antes del montaje, inspeccione con cuidado el muestreador. Compruebe el sampler para asegurarse de que no se daña, todos los tornillos estén colocadas y esté ajustada y el precinto alrededor de la costura formado por las dos mitades está intacta. Ins...

<ol>
	<li>Mendell, M. J., Mirer, A. G., Cheung, K., Tong, M., 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=Respiratory+and+allergic+health+effects+of+dampness,+mold,+and+dampness-related+agents:+a+review+of+the+epidemiologic+evidence.">Respiratory and allergic health effects of dampness, mold, and dampness-related agents: a review of the epidemiologic evidence.</a> Environ Health Perspect. 119 (6), 748-756 (2011).</li><li>Green, B. J., Lemons, A. R., Park, Y., Cox-Ganser, J. M., Park, 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=Assessment+of+fungal+diversity+in+a+water-damaged+office+building.">Assessment of fungal diversity in a water-damaged office building.</a> J Occup Environ Hyg. 14 (4), 285-293 (2017).</li><li>Green, B. J., Lemons, A. R., Park, Y., Cox-Ganser, J. M., Park, 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=Assessment+of+fungal+diversity+in+a+water-damaged+office+building.">Assessment of fungal diversity in a water-damaged office building.</a> J Occup Environ Hyg. , (2016).</li><li>Pitkaranta, 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=Analysis+of+fungal+flora+in+indoor+dust+by+ribosomal+DNA+sequence+analysis,+quantitative+PCR,+and+culture.">Analysis of fungal flora in indoor dust by ribosomal DNA sequence analysis, quantitative PCR, and culture.</a> Appl Environ Microbiol. 74 (1), 233-244 (2008).</li><li>Rittenour, W. 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=Internal+transcribed+spacer+rRNA+gene+sequencing+analysis+of+fungal+diversity+in+Kansas+City+indoor+environments.">Internal transcribed spacer rRNA gene sequencing analysis of fungal diversity in Kansas City indoor environments.</a> Environ Sci Process Impacts. 16 (1), 33-43 (2014).</li><li>Martin, K. J., Rygiewicz, P. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fungal-specific+PCR+primers+developed+for+analysis+of+the+ITS+region+of+environmental+DNA+extracts.">Fungal-specific PCR primers developed for analysis of the ITS region of environmental DNA extracts.</a> BMC Microbiol. 5, 28 (2005).</li><li>Monard, C., Gantner, S., Stenlid, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Utilizing+ITS1+and+ITS2+to+study+environmental+fungal+diversity+using+pyrosequencing.">Utilizing ITS1 and ITS2 to study environmental fungal diversity using pyrosequencing.</a> FEMS Microbiol Ecol. 84 (1), 165-175 (2013).</li><li>Op De Beeck, M., Lievens, B., Busschaert, P., Declerck, S., Vangronsveld, J., Colpaert, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+and+validation+of+some+ITS+primer+pairs+useful+for+fungal+metabarcoding+studies.">Comparison and validation of some ITS primer pairs useful for fungal metabarcoding studies.</a> PLoS One. 9 (6), e97629 (2014).</li><li>Toju, H., Tanabe, A. S., Yamamoto, S., Sato, 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-coverage+ITS+primers+for+the+DNA-based+identification+of+ascomycetes+and+basidiomycetes+in+environmental+samples.">High-coverage ITS primers for the DNA-based identification of ascomycetes and basidiomycetes in environmental samples.</a> PLoS One. 7 (7), e40863 (2012).</li><li>Lemons, A. 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=Microbial+rRNA+sequencing+analysis+of+evaporative+cooler+indoor+environments+located+in+the+Great+Basin+Desert+region+of+the+United+States.">Microbial rRNA sequencing analysis of evaporative cooler indoor environments located in the Great Basin Desert region of the United States.</a> Environ Sci Process Impacts. , (2017).</li><li>Cao, G., Noti, J. D., Blachere, F. M., Lindsley, W. G., Beezhold, D. H. <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+an+improved+methodology+to+detect+infectious+airborne+influenza+virus+using+the+NIOSH+bioaerosol+sampler.">Development of an improved methodology to detect infectious airborne influenza virus using the NIOSH bioaerosol sampler.</a> J Environ Monit. 13 (12), 3321-3328 (2011).</li><li>Soo, J. C., Lee, T., Kashon, M., Kusti, M., Harper, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quartz+in+coal+dust+deposited+on+internal+surface+of+respirable+size+selective+samplers.">Quartz in coal dust deposited on internal surface of respirable size selective samplers.</a> J Occup Environ Hyg. 11 (12), D215-D219 (2014).</li><li>Wang, C. H., 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=Field+evaluation+of+personal+sampling+methods+for+multiple+bioaerosols.">Field evaluation of personal sampling methods for multiple bioaerosols.</a> PLoS One. 10 (3), e0120308 (2015).</li><li>Lindsley, W. G., Schmechel, D., Chen, B. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+two-stage+cyclone+using+microcentrifuge+tubes+for+personal+bioaerosol+sampling.">A two-stage cyclone using microcentrifuge tubes for personal bioaerosol sampling.</a> J Environ Monit. 8 (11), 1136-1142 (2006).</li><li>Rittenour, W. R., Park, J. H., Cox-Ganser, J. M., Beezhold, D. H., Green, B. J. <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+DNA+extraction+methodologies+used+for+assessing+fungal+diversity+via+ITS+sequencing.">Comparison of DNA extraction methodologies used for assessing fungal diversity via ITS sequencing.</a> J Environ Monit. 14 (3), 766-774 (2012).</li><li>ACGIH. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Documentation of the threshold limit values and biological exposure indices. Appendix C: Particle size-selective sampling criteria for airborne particulate matter. , (2001).</li><li>Rodes, C. E., Thornburg, J. W., Ruzer, L. S., Harley, N. 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> Aerosols handbook: measurement, dosimetry, and health effects. , (2005).</li><li>Broadwater, 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=Investigating+a+persistent+odor+at+an+aircraft+seat+manufacturer.">Investigating a persistent odor at an aircraft seat manufacturer.</a> J Occup Environ Hyg. 13 (10), D159-D165 (2016).</li><li>Couch, 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=.">.</a> Health Hazard Evaluation Program: Evaluation of Potential Hazards during Harvesting and Processing Cannabis at an Outdoor Organic Farm. Report No. 2015-0111-3271. , (2017).</li><li>Feinstein, L. M., Sul, W. J., Blackwood, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+bias+associated+with+incomplete+extraction+of+microbial+DNA+from+soil.">Assessment of bias associated with incomplete extraction of microbial DNA from soil.</a> Appl Environ Microbiol. 75 (16), 5428-5433 (2009).</li><li>Keswani, J., Kashon, M. L., Chen, B. T. <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+interference+to+conventional+and+real-time+PCR+for+detection+and+quantification+of+fungi+in+dust.">Evaluation of interference to conventional and real-time PCR for detection and quantification of fungi in dust.</a> J Environ Monit. 7 (4), 311-318 (2005).</li><li>Bellemain, E., Carlsen, T., Brochmann, C., Coissac, E., Taberlet, P., Kauserud, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ITS+as+an+environmental+DNA+barcode+for+fungi:+an+in+silico+approach+reveals+potential+PCR+biases.">ITS as an environmental DNA barcode for fungi: an in silico approach reveals potential PCR biases.</a> BMC Microbiol. 10, 189 (2010).</li><li>Farrelly, V., Rainey, F. A., Stackebrandt, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+genome+size+and+rrn+gene+copy+number+on+PCR+amplification+of+16S+rRNA+genes+from+a+mixture+of+bacterial+species.">Effect of genome size and rrn gene copy number on PCR amplification of 16S rRNA genes from a mixture of bacterial species.</a> Appl Environ Microbiol. 61 (7), 2798-2801 (1995).</li><li>Vesper, S., 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=Development+of+an+Environmental+Relative+Moldiness+index+for+US+homes.">Development of an Environmental Relative Moldiness index for US homes.</a> J Occup Environ Med. 49 (8), 829-833 (2007).</li></ol>

Determinar la diversidad fúngica dentro de un entorno de trabajo utilizando enfoques basados en la secuenciación ha mejorado la evaluación de identificación y exposición de peligro de hongos. Con este enfoque ha permitido la detección de muchas otras especies fúngicas que a menudo no se detectan mediante cultivo o métodos de evaluación basados en la microscopía. Aquí se presenta un método para el muestreo de bioaerosoles de ambientes interiores y en el trabajo y la extracción de DNA genómico de muestras de ...

Exposiciones de hongos en ambientes de interior y trabajo pueden causar morbilidades respiratorias, incluida la sensibilización alérgica y asma1. Identificación de los riesgos de hongos es importante para evaluar el riesgo y prevenir la exposición de los trabajadores. Estos peligros de hongos pueden ser el resultado de contaminación interior, intrusión de aire exterior o perturbaciones ambientales ocurridos en el transporte de materiales fungicidos en áreas donde los trabajadores están presentes2. Métodos para evaluar la exposición de hongos han incluido muestreo de cultura viable así como identificación microscópica de las esporas de hongos. Estos enfoques tienen varias limitaciones y a menudo pasan por alto muchas especies de hongos que podrían contribuir a la carga fúngica total3. Enfoques basados en la cultura sólo pueden distinguir los organismos fúngicos viables que pueden ser cultivados en medios nutritivos. Identificación de esporas de hongos a nivel de especie mediante microscopia puede ser confundido por esporas comparten morfologías similares. Ambos métodos son altamente dependientes de micólogos para analizar e identificar la especie fúngica, con muchos restantes no identificados.
Para mejorar metodologías existentes utilizados en identificación de riesgos laborales y evaluaciones de la exposición, muchos investigadores han recurrido a las tecnologías moleculares. Enfoques basados en la secuencia para evaluar la diversidad microbiana en ambientes de interior y trabajo han revelado un espectro más amplio de especies fúngicas encontradas en comparación con métodos como la microscopía y cultivo viable3,4 ,5. El método presentado aquí describe el muestreo de aire de ambientes laborales y la extracción de ADN genómico para la identificación de riesgos potenciales de hongos. Identificación de riesgos se logra mediante la secuenciación de regiones que son altamente variables entre los hongos y se han utilizado comúnmente para distinguir especies de hongos6,7, el espaciador transcrito interno ribosomal nuclear, o su, 8,9. Muchas especies encuentran en ajustes ocupacionales, tales como algunas especies pertenecientes al phylum Basidiomycota, no son identificables en la cultura viable y son difíciles de diferenciar microscópicamente. Estos hongos se han observado en la alta abundancia relativa dentro de ambientes interiores y ocupacionales determinado por la secuencia hongos ITS regiones3,4,10. SU secuenciación ha proporcionado un mayor conocimiento en la diversidad de hongos encontrados en ambientes de interior y trabajo.
El protocolo descrito aquí detalles de los métodos usados para recolectar, extraer y amplificar regiones de su fungicidas de bioaerosoles para análisis de la secuencia. Este enfoque utiliza el Instituto Nacional de seguridad ocupacional y salud (NIOSH) sampler de aerosol de ciclón de dos etapas recoger las partículas en el aire. Este muestreador se desarrolló para recoger los bioaerosoles y respirable se separa (≤4 μm de diámetro aerodinámico) y no-respirables (> 4 μm de diámetro aerodinámico) las partículas, que permite la identificación de organismos fúngicos dentro de ambientes interiores que son los más probabilidades de ser inhalada por un trabajador11. Otros muestreadores de aire, incluyendo samplers de ciclón, están disponibles en el mercado que tienen la capacidad para recoger las partículas dentro de la gama respirable (< 4 μm) usando filtros de12,13. Por el contrario, el sampler de aerosol del ciclón de dos etapas NIOSH separa especies fúngicas basadas en su diámetro aerodinámico en tubos de polipropileno, desechables que pueden ser procesados inmediatamente para aplicaciones posteriores14.
Los procesos de extracción de DNA genómico y amplificación de las regiones de su fungicidas se detallan en el presente Protocolo. Las metodologías de extracción presentadas han sido desarrolladas específicamente para la extracción de ADN genómico de hongos y bacterias, como muchos kits comerciales dirigidos a células de mamíferos, bacterias o específicamente de levaduras15. Los cebadores utilizados en este estudio se seleccionan según su cobertura global de los hongos ITS 1 y 2 sus regiones4,5. La secuencia de estas regiones permite la comparación de muchas secuencias de sus bancos, los incluidos esa secuencia la región su 1, 2 de su región o regiones el su 1 y 2 su. La diversidad fúngica de muestras de aire recogidas en un ajuste interior utilizando que estos métodos se muestran, revelando un número importante de secuencias a lo phyla Ascomycota y Basidiomycota, así como otras secuencias pertenecientes a los phyla fungicida menos dominante, tales como Zygomycota. La amplia diversidad de hongos secuencias identificados con este enfoque no sería capturar utilizando metodologías de identificación de riesgo tradicionales como cultivo o microscopia. Secuenciación de regiones ITS hongos proporciona un método mejorado para identificar riesgos de hongos y permitir una mejor comprensión de las exposiciones de hongos interiores y trabajo.

<table>
	<tbody>
		<tr>
			<td>NIOSH BC251 bioaerosol cyclone sampler</td>
			<td>NIOSH</td>
			<td>BC251</td>
			<td>The NIOSH sampler is not yet commercially available. Please contact William Lindsley, PhD (wlindsley@cdc.gov) for information on obtaining the NIOSH sampler</td>
		</tr>
		<tr>
			<td>Fisherbrand Sterile Microcentrifuge Tubes with Screw Caps</td>
			<td>Fisher Scientific</td>
			<td>02-681-373</td>
			<td>1.5 mL polypropylene microcentrifuge tubes for air sampling; screw top threading must match the threading of the NIOSH sampler</td>
		</tr>
		<tr>
			<td>Falcon 15 mL Conical Centrifuge Tubes</td>
			<td>Corning</td>
			<td>352096</td>
			<td>15 mL polypropylene tubes for air sampling</td>
		</tr>
		<tr>
			<td>Clean Room Vinyl Tape, Easy-Remove, 1/4&#34; Width</td>
			<td>McMaster-Carr</td>
			<td>76505A1</td>
			<td>sealing tape</td>
		</tr>
		<tr>
			<td>Filter Cassette, Clear Styrene, 37 mm</td>
			<td>SKC Inc.</td>
			<td>225-3LF</td>
			<td>3-piece sampling cassette (no filter). Contains: cassette base, extension cowl, cassette cap and inlet/outlet plugs</td>
		</tr>
		<tr>
			<td>PTFE hydrophobic fluoropore membrane filters, 3.0 &#181;m, 37 mm</td>
			<td>EMD Millipore</td>
			<td>FSLW03700</td>
			<td>Contains: 37 mm, 3.0 &#181;m PTFE filters and support pads</td>
		</tr>
		<tr>
			<td>Fisherbrand filter forceps</td>
			<td>Fisher Scientific</td>
			<td>09-753-50</td>
			<td>filter forceps</td>
		</tr>
		<tr>
			<td>Model 502 Precision PanaPress</td>
			<td>PanaVise</td>
			<td>502</td>
			<td>pneumatic cassette press is constructed from this precision arbor press</td>
		</tr>
		<tr>
			<td>Scotch Super 33+ vinyl electrical tape</td>
			<td>McMaster-Carr</td>
			<td>76455A21</td>
			<td>19 mm tape</td>
		</tr>
		<tr>
			<td>Multi-purpose Calibration Jar, Large</td>
			<td>SKC Inc.</td>
			<td>225-112</td>
			<td>calibration jar</td>
		</tr>
		<tr>
			<td>Universal PCXR4 Sample Pump</td>
			<td>SKC Inc.</td>
			<td>224-PCXR4</td>
			<td>sampling pump</td>
		</tr>
		<tr>
			<td>Mass Flowmeter 4140</td>
			<td>TSI Inc.</td>
			<td>4140</td>
			<td>flow meter</td>
		</tr>
		<tr>
			<td>Roche High Pure PCR Template Kit</td>
			<td>Roche Diagnostics</td>
			<td>11796828001</td>
			<td>Kit used for genomic DNA extraction. Contains: Lysis buffer, Binding buffer, Proteinase K, Inhibitor removal buffer, Wash buffer, Elution buffer, Glass fiber filter tubes and 2 ml collection tubes</td>
		</tr>
		<tr>
			<td>Fisherbrand 2 mL Reinforced Polypropylene Screw Cap Tubes with Caps</td>
			<td>Fisher Scientific</td>
			<td>15340162</td>
			<td>2 mL reinforced tubes for bead homogenization</td>
		</tr>
		<tr>
			<td>Glass beads, acid washed, 212-300 &#181;m</td>
			<td>Sigma-Aldrich</td>
			<td>G1277</td>
			<td>glass beads</td>
		</tr>
		<tr>
			<td>Fisher Scientific Bead Mill 24 Homogenizer</td>
			<td>Fisher Scientific</td>
			<td>15-340-163</td>
			<td>bead homogenizer</td>
		</tr>
		<tr>
			<td>CelLytic B Cell Lysis Reagent, 10X</td>
			<td>Sigma-Aldrich</td>
			<td>C8740</td>
			<td>lysis reagent</td>
		</tr>
		<tr>
			<td>Platinum Taq polymerase</td>
			<td>Invitrogen</td>
			<td>10966-018</td>
			<td>Contains: Platinum Taq polymerase, 10X PCR buffer (no MgCl2), 50 mM MgCl2, KB Extender</td>
		</tr>
		<tr>
			<td>dNTP Mix</td>
			<td>Invitrogen</td>
			<td>18427-088</td>
			<td>10 mM dNTP mix</td>
		</tr>
		<tr>
			<td>QIAquick PCR Purification Kit</td>
			<td>Qiagen</td>
			<td>28106</td>
			<td>Kit used to purify fungal amplicons. Contains: Buffer PB (binding buffer), Buffer PE (washing buffer), Buffer EB (elution buffer), pH Indicator dye (optional), and GelPilot loading dye</td>
		</tr>
		<tr>
			<td>Owl EasyCast Mini Gel Electrophoresis System</td>
			<td>Thermo Fisher</td>
			<td>B1 or B2</td>
			<td></td>
		</tr>
		<tr>
			<td>TrackIt 1 KB Plus DNA Ladder</td>
			<td>Thermo Fisher</td>
			<td>10488-085</td>
			<td>DNA ladder</td>
		</tr>
	</tbody>
</table>

collection and extraction of occupational air samples for analysis of fungal dna

Los métodos tradicionales de identificación de hongos exposición en ambientes laborales, como cultura y enfoques basados en la microscopía, tienen varias limitaciones que han dado lugar a la exclusión de muchas especies. Avances en el campo durante las últimas dos décadas han llevado a los investigadores de salud recurrir a enfoques moleculares para la identificación de riesgos de hongos. Estos métodos han resultado en la detección de muchas especies dentro de ambientes de interiores y profesionales que no han sido detectados usando métodos tradicionales. Los datos de este protocolo muestras un enfoque para determinar la diversidad fúngica en aire a través de la extracción de ADN genómica, amplificación, secuenciación identificación taxonómica de hongos interno transcribieron regiones del espaciador (ITS). LOS resultados de la secuenciación en la detección de muchas especies de hongos que son no detectado o difíciles de identificar a nivel de especie mediante cultivo o microscopia. Mientras que estos métodos no proporcionan medidas cuantitativas de la carga fúngica, ofrecen un nuevo enfoque para la identificación de los peligros y puede utilizarse para determinar la riqueza total de especies y la diversidad dentro de un entorno laboral.

Puede evaluarse la distribución de las especies dentro de un entorno con abundancia relativa en la determinación de la cantidad de clones de cada OTU identificados en las muestras de aire. Figura 6 es un gráfico de la corona que representan las especies taxonómicamente colocadas dentro de un ambiente interior después de 60 min de muestreo de aire. Se puede observar que el entorno contiene una variedad de especies dentro de dos grande phyla fungicida, Asc...

Watch this Scientific Journal Video about Collection and Extraction of Occupational Air Samples for Analysis of Fungal DNA at JoVE.com

Collection and Extraction of Occupational Air Samples for Analysis of Fungal DNA

Determinación de la diversidad fúngica dentro de un entorno es un método utilizado en los estudios de salud ocupacional para identificar riesgos para la salud. Este protocolo describe la extracción de ADN de muestras de aire ocupacional para la amplificación y secuenciación de regiones ITS hongos. Este método detecta muchas especies de hongos que pueden ser pasada por alto por los métodos de evaluación tradicionales.

Colección y extracción de muestras de aire profesional para análisis de ADN fúngico

Traditional methods of identifying fungal exposures in occupational environments, such as culture and microscopy-based approaches, have several ...

The overall goal of this air sampling and DNA extraction methodology is to obtain fungal genomic DNA that can amplified, sequenced, and taxonomically placed to identify potential fungal hazards within occupational settings. This method can help answer key questions in the occupational exposure assessment field, such as what fungal hazards are workers exposed to that may result in negative health effects. The main advantage of this technique is that fungal species that remain undetected using culture or microscopy-based methods can be elucidated using sequencing-based approaches.To assemble the air-sampling filter cassette, place a cellulose filter support pad on the gridded surface of the base piece, then, with the help of filter forceps, place a filter on top of the filter support pad with the collection side facing upwards. After assembling, seal the filter cassette by inserting the extension cowl and pressing it down tightly and evenly with a manual or pneumatic press. Then, fit the assembled cassette on top of the NIOSH aerosol sampler and push down as much as possible.Use a piece of 19-millimeter tape to wrap around the outside of the filter cassette and sampler holding the filter cassette in place and acting as a back-up seal to prevent leaks. Screw the collection tubes tightly and fully into the sampler until they bottom out and wrap the sealing tape around the tubes acting as secondary seal against leakage. To conduct personal aerosol sampling, place the sampler within the person's breathing zone.Attach the sampler to the lapel, shoulder, or chest and then keep the sampling pump at the waist level or in a backpack. Turn the pumps on and check after a minute if the pump is functioning. Upon completing air sampling, collect the air sampler from the subject.Remove the sealing tape, unscrew the tubes, and then put a cap on them. Place the third piece of filter cassette over the filter. First, wipe the sampling cassette with 70%ethanol, then use a cassette opening tool to open the sampling cassette while working in a Class II biological safety cabinet.Next, use a filter lifter to lift the support pad and filter upwards. Then, use filter forceps to remove the filter and place it in a sterile Petri dish. Cut the filter into six equal pieces with a steril scalpel and then place them in a two-milliliter reinforced tube containing 300 milligrams of 200 to 500 micrometer glass beads.Immerse the filter-containing tube in liquid nitrogen for 30 seconds and then quickly place it in a bead mill homogenizer at a speed of 4.5 meters per second for 30 seconds. Add 0.5 milliliters of lysis buffer to tubes containing the remaining small pieces of intact filter, then add 0.3 milliliter of lysis buffer to the 15 and 1.5 milliliter air sampler collection tubes and vortex the tubes in an upright and inverted position for 10 to 15 seconds respectively. Transfer the lysis buffer from each collection tube to two-milliliter reinforced tubes containing 300 milligrams of glass beads.Process the tubes in the bead mill homogenizer for 30 seconds, then centrifuge the samples at 20, 000 times gravity for one minute at 22 degrees Celsius. After centrifugation, transfer the supernatant in a sterile 1.5-milliliter microcentrifuge tube and again centrifuge the supernatant at 20, 000 times gravity for one minute at 22 degrees Celsius. After adding 30 microliters of lysis reagent, incubate the tubes at 37 degrees Celsius for 15 minutes.Then, add 0.2 milliliter of binding buffer and 100 micrograms per milliliter of Proteinase K to the tube, then leave the tubes for incubation in a block heater at 70 degrees Celsius for 10 minutes. Finally, add 100 microliters of isopropanol to each tube. Then, place glass fiber filter tubes with a capacity of 700 microliters in two-milliliter collection tubes and transfer the extract solutions into it.Following transfer, centrifuge the collection tubes at 20, 000 times gravity for 30 seconds at 22 degrees Celsius. After centrifugation, insert the glass filter fiber in fresh collection tubes and discard the collection tube. To each tube add 0.5 milliliter of inhibitor removal buffer and conduct centrifugation at 20, 000 times gravity for 30 seconds at 22 degrees Celsius.Discard the collection tube after centrifugation and place the filter tubes into new collection tubes. Then, add 0.5 milliliter of wash buffer to each tube and again subject to centrifugation at 20, 000 times gravity for 30 seconds at 22 degrees Celsius. Discard the collection tube and replace with fresh ones after the centrifugation.Again, add 0.5 milliliter of wash buffer to each tube and centrifuge at 20, 000 times gravity for 30 seconds at 22 degrees Celsius. To remove any residual wash buffer, finally centrifuge the collection tubes at 20, 000 times gravity for one minute at 22 degrees Celsius and discard the collection tubes and replace them with fresh ones. After adding 100 microliters of warm elution buffer, incubate the tubes on the lab bench at room temperature for one to two minutes and centrifuge the collection tubes at 20, 000 times gravity for 30 seconds at 22 degrees Celsius.Place the filter tubes in a sterile 1.5-milliliter microcentrifuge tube and reapply the eluates for another round centrifugation. Use 0.5 milliliter PCR tubes to set up 50-microliter reactions in triplicate with five microliters of already-extracted DNA for each reaction, then program the thermocycler and start the cycle. Mix all three PCR reactions together in sterile 1.5 milliliter microcentrifuge tubes.Add 750 microliters of binding buffer and mix thoroughly by pipetting up and down 10 times. Add 450 microliters of the total mixture to spin columns inserted in collection tubes and start centrifuging at 17, 900 times gravity for 30 seconds, then discard the filtrate and add the remaining 450 microliters of the mixture for a second round of centrifugation. Again, discard the filtrate and add 750 microliters of wash buffer to the spin columns and centrifuge at 17, 900 times gravity for 30 seconds at 22 degrees Celsius.Finally, discard the filtrate and re-spin the empty columns at 17, 900 times gravity for one minute at 22 degrees Celsius. After transferring the spin columns to 1.5-milliliter sterile microcentrifuge tubes, pipette 45 microliters of elution buffer and incubate the tubes on the lab bench at room temperature for five minutes. Then, centrifuge the columns at 17, 900 times gravity for one minute at 22 degrees Celsius.Immerse a 1%agarose gel in one-fold TAE buffer in an electrophoresis chamber, then mix two microliters of five-fold loading buffer with eight microliters of amplified DNA. Finally, load the entire 10 microliters of the sample on the gel along with the DNA ladder. Run the gel at 75 volts for approximately 90 minutes.A representative agarose gel demonstrates amplification of internal transcribed spacer regions of fungal genomic DNA derived from occupational air samples. The lane on the extreme left side represents the DNA marker lane. The bands on the right represent the internal transcribed spacer regions amplified from different occupational air samples with sizes ranging from 750 to 1, 000 base pairs.A representative Krona chart shows the presence of diverse taxonomic fungal species in an indoor environment. The NIOSH bio-aerosol cyclone sampler was used in homes to collect bio-aerosols for one hour to determine the fungal species present. Tabular data represents the diversity and richness indices of fungal species in indoor environments.Data shows higher Chao-1 Richness indices, Shannon Diversity indices, and Bray-Curtis dissimilarity coefficients in air-conditioned and evaporative cooler environments. After watching this video, you should have a good understanding of how to collect indoor and occupational air samples and extract genomic DNA for the analysis of microbial populations. While attempting this procedure, it is important to remember to utilize the best aseptic methods to prevent microbiological contamination of the samples.

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