Name: microbiota analysis using two-step pcr and next-generation 16s rrna gene sequencing
Uploaded: 2019-10-15T12:30:00
Description: Watch this Scientific Journal Video about Microbiota Analysis Using Two-step PCR and Next-generation 16S rRNA Gene Sequencing at JoVE.com

The authors acknowledge funding from the NIAID/NIH (1R01AI137075-01), the Carver Trust Medical Research Initiative Grant, and the University of Iowa Environmental Health Sciences Research Center, NIEHS/NIH (P30 ES005605).

The protocol was approved by the Institutional Animal Care and Use Committee of the University of Iowa.
1. Fecal Sample Collection and Handling
<ol>
	<li>Sterilize the divider boxes (see Table of Materials, Supplementary Figure 1) with 70% ethanol.</li>
	<li>Pre-label microcentrifuge tubes (one per mouse) with the sample ID and treatment group (if applicable).</li>
	<li>Place the mice in sterilized divider boxes and allow them to defecate normally for up to ...

The described protocol is simple, with easy-to-follow steps to perform microbiome profiling using 16S rRNA metagenomic sequencing from a large number of biospecimens of interest. Next-generation sequencing has transformed microbial ecology studies, especially in human and pre-clinical disease models31,32. The main advantage of this technique is its ability to successfully analyze complex microbial compositions (culturable and non-culturable microbes) in a given b...

Microbiota refers to a collection of microorganisms (bacteria, viruses, archaea, bacteriophages, and fungi) living in a particular environment, and the microbiome refers to the collective genome of resident microorganisms. As bacteria are one of the most abundant microbes in humans and mice, this study is focused only on bacterial profiling. The human gut is colonized by trillions of bacteria and hundreds of bacterial strains1. The normal gut microbiota plays a vital role in maintaining a healthy state in the host by regulating functions (i.e., maintenance of an intact intestinal barrier, food metabolism, energy homeostasis, inhibition of colonization by pathogenic organisms, and regulation of immune responses)2,3,4,5. Compositional perturbations of the gut microbiota (gut dysbiosis) have been linked to a number of human diseases, including gastrointestinal disorders6, obesity7,8, stroke9, cancer10, diabetes8,11, rheumatoid arthritis12, allergies13, and central nervous system-related diseases such as multiple sclerosis (MS)14,15 and Alzheimer&#39;s disease (AD)8,16. Therefore, in recent years, there has been growing interest in tools for identifying bacterial composition at different body sites. A reliable method should have characteristics such as being high-throughput and easy-to-use, having the ability to classify bacterial microbiota with high resolution, and being low-cost.
Culture-based microbiological techniques are not sensitive enough to identify and characterize the complex gut microbiome due to the failure of several gut bacteria to grow in culture. The advent of the sequencing-based technology, especially 16S rRNA-based metagenomic sequencing, has overcome some of these challenges and transformed microbiome research17. Advanced 16S rRNA-based sequencing technology has helped in establishing a critical role for the gut microbiome in human health. The Human Microbiome Project, a National Institutes of Health initiative18, and the MetaHIT project (a European initiative)19 have both helped in establishing a basic framework for microbiome analysis. These initiatives helped kick-start multiple studies to determine the role of the gut microbiome in human health and disease.
A number of groups have shown gut dysbiosis in patients with inflammatory diseases12,14,15,20,21,22. Despite being widely used for taxonomic profiling due to the ability to multiplex and low costs, there are no uniform protocols for 16S rRNA-based taxonomic profiling. Another limitation is the low resolution of taxonomic assignment owing to smaller sequencing reads (150 bp or 250 bp) and use of only forward sequencing read (R1) due to low quality reverse sequencing reads (R2). However, advances in sequencing technology have helped to overcome some of these challenges, such as the ability to sequence longer reads using paired-end reads (e.g., Illumina MiSeq 2x300bp).
The present sequencing technology can sequence 600 bp good quality reads, which allows merging of R1 and R2 reads. These merged longer R1 and R2 reads allow better taxonomic assignments, especially with open-access R-based Divisive Amplicon Denoising Algorithm-2 (DADA2) platform. DADA2 utilizes amplicon sequence variant (ASV)-based assignments instead of operational taxonomic unit (OTU) assignments based on 97% similarity utilized by QIIME23. ASV matches result in an exact sequence match in the database within 1&#8211;2 nucleotides, which leads to assignment at genus and species levels. Thus, the combination of longer, good quality paired-end reads and better taxonomic assignment tools (such as DADA2) have transformed microbiome studies.
Provided here is a step-by-step guide for performing bacterial profiling using two-step amplification of the V3&#8211;V4 region of 16S rRNA and data analysis using DADA2, Phyloseq, and METAGENassist pipelines. For this study, human leukocyte antigen (HLA) class II transgenic mice are used, as certain HLA class II alleles are linked with a predisposition to autoimmune diseases such as MS20,24,25. However, the importance of HLA class II genes in regulating the composition of gut microbiota is unknown. It is hypothesized that the HLA class II molecule will influence gut microbial community by selecting for specific bacteria. Major histocompatibility complex (MHC) class II knockout mice (AE.KO) or mice expressing human HLA-DQ8 molecules (HLA-DQ8)24,25,26 were used in order to understand the importance of HLA class II molecules in shaping the gut microbial community. It is believed that this complete and simplified workflow with R-based data analysis will serve as an excellent tool for researchers interested in performing microbiome profiling studies.
The generation of mice lacking endogenous murine MHC class II genes (AE.KO) and AE-/-.HLA-DQA1*0103, DQB1*0302 (HLA-DQ8) transgenic mice with a C57BL/6J background has been described previously26. Fecal samples are collected from mice of both sexes (8&#8211;12 weeks of age). Mice were previously bred and maintained in the University of Iowa animal facility as per the NIH and institutional guidelines. Contamination control strategies such as weaning of the mice inside a laminar flow cabinet, changing of gloves between different strains of mice, and proper maintenance of mice are critical steps for profiling of gut microbiome.
Proper personal protective equipment (PPE) are highly recommended during the entire procedure. Appropriate negative controls should be included when performing DNA isolation, PCR1 and PCR2 amplification, and sequencing steps. Use of sterile, DNase-free, RNase-free, and pyrogen-free supplies is recommended. Designated pipettor for microbiome work and filtered pipette tips should be used throughout the protocol. Microbiota analysis consists of seven steps: 1) fecal sample collection and processing; 2) extraction of DNA; 3) 16S rRNA gene amplification; 4) DNA library construction using indexed PCR; 5) clean-up and quantification of indexed PCR (library); 6) MiSeq sequencing; and 7) data processing and sequence analysis. A schematic diagram of all protocol steps is shown in Figure 1.

<table>
	<tbody>
		<tr>
			<td>1.5 ml Natural Microcentriguge Tube</td>
			<td>USA, Scientific</td>
			<td>1615-5500</td>
			<td>Fecal collection</td>
		</tr>
		<tr>
			<td>3M hand applicator squeegee PA1-G</td>
			<td>3M, MN, US</td>
			<td>7100038651</td>
			<td>Squeeger for proper sealing of PCR Plate</td>
		</tr>
		<tr>
			<td>Agencourt AMPure XP</td>
			<td>Beckman Coulter, IN, USA</td>
			<td>A63880</td>
			<td>PCR Purification, NGS Clean-up, PCR clean-up</td>
		</tr>
		<tr>
			<td>Agilent DNA 1000 REAGENT</td>
			<td>Agilent Technologies, CA, USA</td>
			<td>5067-1504</td>
			<td>DNA quantification and quality control</td>
		</tr>
		<tr>
			<td>Bioanalyzer DNA 1000 chip</td>
			<td>Agilent Technologies, CA, USA</td>
			<td>5067-1504</td>
			<td>DNA quantification and quality control</td>
		</tr>
		<tr>
			<td>Index Adopter Replacement Caps</td>
			<td>Illumina, Inc., CA, USA</td>
			<td>15026762</td>
			<td>New cap for Index 1 and 2 adopter primer</td>
		</tr>
		<tr>
			<td>DNeasy PowerLyzer PowerSoil Kit</td>
			<td>MoBio now part of QIAGEN, Valencia, CA, USA</td>
			<td>12855-100</td>
			<td>DNA isolation</td>
		</tr>
		<tr>
			<td>KAPA HiFi HotStart ReadyMiX (2X)</td>
			<td>Kapa Biosystem, MA, USA</td>
			<td>KK2602</td>
			<td>PCR ready mix for Amplicon PCR1 and Indexed PCR2</td>
		</tr>
		<tr>
			<td>Lewis Divider Boxes</td>
			<td>Lewis Bins, WI, US</td>
			<td>ND03080</td>
			<td>Fecal collection</td>
		</tr>
		<tr>
			<td>Magnetic stand</td>
			<td>New England BioLabs, MA, USA</td>
			<td>S1509S</td>
			<td>For PCR clean-up</td>
		</tr>
		<tr>
			<td>MicroAmp Fast Optical 96-Well Reaction Plate</td>
			<td>Applied Biosystems, Thermo Fisher Scientific, CA, USA</td>
			<td>4346906</td>
			<td>PCR Plate</td>
		</tr>
		<tr>
			<td>MicroAmp Optical Adhesive Film</td>
			<td>Applied Biosystems, Thermo Fisher Scientific, CA, USA</td>
			<td>4311971</td>
			<td>PCR Plate Sealer</td>
		</tr>
		<tr>
			<td>Microfuge 20 Centrifuge</td>
			<td>Beckman Coulter, IN, USA</td>
			<td>B30154</td>
			<td>Centrifuge used for DNA isolation</td>
		</tr>
		<tr>
			<td>MiSeq Reagent Kit (600 cycles)v.3</td>
			<td>Illumina, Inc., CA, USA</td>
			<td>MS-102-3003</td>
			<td>For MiSeq Sequencing</td>
		</tr>
		<tr>
			<td>Nextera XT DNA Library Preparation Kit</td>
			<td>Illumina, Inc., CA, USA</td>
			<td>FC-131-1001</td>
			<td>16S rRNA DNA Library Preparation</td>
		</tr>
		<tr>
			<td>Reagent Reservoirs Multichannel Trays</td>
			<td>ASI, FL,USA</td>
			<td>RS71-1</td>
			<td>For Pooling of PCR2 Product</td>
		</tr>
		<tr>
			<td>Plate Cetrifuge</td>
			<td>Thermo Fisher Scientific, CA, USA</td>
			<td>75004393</td>
			<td>For PCR reagent mixing and removing air bubble from Plate</td>
		</tr>
		<tr>
			<td>PhiX Control</td>
			<td>Illumina, Inc., CA, USA</td>
			<td>FC-110-3001</td>
			<td>For MiSeq Sequencing control</td>
		</tr>
		<tr>
			<td>Microbiome DNA Purification Kit</td>
			<td>Thermo Fisher Scientific, CA, USA</td>
			<td>A29789</td>
			<td>For purification of PCR1 product</td>
		</tr>
		<tr>
			<td>PowerLyzer 24 Homogenizer</td>
			<td>Omni International, GA, USA</td>
			<td>19-001</td>
			<td>Bead beater for DNA Isolation</td>
		</tr>
		<tr>
			<td>Qubit dsDNA HS (High Sensitivity) assay kit</td>
			<td>Thermo Fisher Scientific, CA, USA</td>
			<td>Q32854</td>
			<td>DNA quantification</td>
		</tr>
		<tr>
			<td>TruSeq Index Plate Fixture</td>
			<td>Illumina, Inc., CA, USA</td>
			<td>FC-130-1005</td>
			<td>For Arranging of the index primers</td>
		</tr>
		<tr>
			<td>Vertical Dividers (large)</td>
			<td>Lewis Bins, WI, US</td>
			<td>DV-2280</td>
			<td>Fecal collection</td>
		</tr>
		<tr>
			<td>Vertical Dividers (small)</td>
			<td>Lewis Bins, WI, US</td>
			<td>DV-1780</td>
			<td>Fecal collection</td>
		</tr>
	</tbody>
</table>

microbiota analysis using two-step pcr and next-generation 16s rrna gene sequencing

The human gut is colonized by trillions of bacteria that support physiologic functions such as food metabolism, energy harvesting, and regulation of the immune system. Perturbation of the healthy gut microbiome has been suggested to play a role in the development of inflammatory diseases, including multiple sclerosis (MS). Environmental and genetic factors can influence the composition of the microbiome; therefore, identification of microbial communities linked with a disease phenotype has become the first step towards defining the microbiome&#8217;s role in health and disease. Use of 16S rRNA metagenomic sequencing for profiling bacterial community has helped in advancing microbiome research. Despite its wide use, there is no uniform protocol for 16S rRNA-based taxonomic profiling analysis. Another limitation is the low resolution of taxonomic assignment due to technical difficulties such as smaller sequencing reads, as well as use of only forward (R1) reads in the final analysis due to low quality of reverse (R2) reads. There is need for a simplified method with high resolution to characterize bacterial diversity in a given biospecimen. Advancements in sequencing technology with the ability to sequence longer reads at high resolution have helped to overcome some of these challenges. Present sequencing technology combined with a publicly available metagenomic analysis pipeline such as R-based Divisive Amplicon Denoising Algorithm-2 (DADA2) has helped advance microbial profiling at high resolution, as DADA2 can assign sequence at the genus and species levels. Described here is a guide for performing bacterial profiling using two-step amplification of the V3-V4 region of the 16S rRNA gene, followed by analysis using freely available analysis tools (i.e., DADA2, Phyloseq, and METAGENassist). It is believed that this simple and complete workflow will serve as an excellent tool for researchers interested in performing microbiome profiling studies.

As MHC class II molecules (HLA in humans) are central players in the adaptive immune response and show strong associations with a predisposition to MS24,25,26, it was hypothesized that the HLA class II molecule would influence gut microbial composition. Therefore, mice lacking the MHC class II gene (AE.KO) or expressing human HLA-DQ8 gene (HLA-DQ8) were utilized to understand the importance of HLA class II molecules in shaping t...

Watch this Scientific Journal Video about Microbiota Analysis Using Two-step PCR and Next-generation 16S rRNA Gene Sequencing at JoVE.com

Microbiota Analysis Using Two-step PCR and Next-generation 16S rRNA Gene Sequencing

Described here is a simplified standard operating procedure for microbiome profiling using 16S rRNA metagenomic sequencing and analysis using freely available tools. This protocol will help researchers who are new to the microbiome field as well as those requiring updates on methods to achieve bacterial profiling at a higher resolution.

The human gut is colonized by trillions of bacteria that support physiologic functions such as food metabolism, energy harvesting, and regulation of the ...

Profiling of microbiome is the first step toward defining the role of microbiome in health and disease.Here, we are describing a simple procedure for isolating high-quality bacterial DNA from fecal sample preparing library, performing 16SR RNA and a meta genomic sequencing and microbiome data analysis.This protocol will help researchers new to microbiome field, as well as researchers working in microbiome field in establishing the microbiome pipeline in their lab.This protocol can be extended for profiling of microbiome from other bio specimens such as nasal, oral, or skin samples of animal and human subjects.Bead picking is the most important steps as all downstream steps are depend on high quality DNA.Proper sealing of preserve plate is important as incomplete sealing might lead to the oppressing of amplified product resulting in low quality sequencing data.To begin, sterilize the divider boxes with 70%ethanol.Place the mice in sterilized divider boxes and allow them to defecate normally for up to one hour.Use sterile forceps to collect the fecal pellets in an empty pre-labeled 1.5 milliliter micro centrifuge tube.Enclose the tube securely.Sterilize the forceps with 70%ethanol, followed by a germicidal disposable wipe, after collecting fecal from each mouse.Weigh 200 milligrams of fecal pellets into a 1.5 milliliter micro centrifuge tube, with 0.1 milliliter glass beads, and place the bead tube into a bead beating homogenizer and homogenize the samples for 45 seconds at room temperature, at a speed of 4.5 meters per second.Extract DNA as per instructions of the kit manufacturer and elute DNA in a 1.5 milliliter micro centrifuge tube.After isolating DNA, quantify the isolated DNA by loading 1 microliter of the DNA on a fluorometer.Setup 16S ribosomal RNA gene amplification PCR1 in a 96-Well PCR plate, using a 25 microliter reaction volume.Using a multi-channel pipette, add 40 nano grams of DNA, 13.5 micro liters of 2X high-fidelity polymerase enzyme mix, containing buffer, plus DNTPs in forward and reverse primer.Seal the PCR plate properly from the top to the bottom in along all four edges.And centrifuge at 1000 times G at 20

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Biology

Fluorescence-microscopy Screening and Next-generation Sequencing: Useful Tools for the Identification of Genes Involved in Organelle Integrity

This protocol describes a fluorescence microscope-based screening of Arabidopsis seedlings and describes how to map recessive mutations that alter the subcellular distribution of a specific tagged fluorescent marker in the secretory pathway. Arabidopsis is a powerful biological model for genetic studies because of its genome size, generation time, and conservation of molecular mechanisms among kingdoms. The array genotyping as an approach to map the mutation in alternative to the traditional method based on molecular markers is advantageous because it is relatively faster and may allow the mapping of several mutants in a really short time frame. This method allows the identification of proteins that can influence the integrity of any organelle in plants. Here, as an example, we propose a screen to map genes important for the integrity of the endoplasmic reticulum (ER). Our approach, however, can be easily extended to other plant cell organelles (for example see1,2), and thus represents an important step toward understanding the molecular basis governing other subcellular structures.

A fundamental quest in cell biology is to define the mechanisms that underlie the identity of the organelles that make eukaryotic cells. Here we propose a method to identify the genes responsible for the morphological and functional integrity of plant organelles using fluorescence microscopy and next-generation sequencing tools.

This protocol describes a fluorescence microscope-based screening of Arabidopsis seedlings and describes how to map recessive mutations that alter the ...

Next-generation Sequencing of 16S Ribosomal RNA Gene Amplicons

One of the major questions in microbial ecology is &#8220;who is there?&#8221; This question can be answered using various tools, but one of the long-lasting gold standards is to sequence 16S ribosomal RNA (rRNA) gene amplicons generated by domain-level PCR reactions amplifying from genomic DNA. Traditionally, this was performed by cloning and Sanger (capillary electrophoresis) sequencing of PCR amplicons. The advent of next-generation sequencing has tremendously simplified and increased the sequencing depth for 16S rRNA gene sequencing. The introduction of benchtop sequencers now allows small labs to perform their 16S rRNA sequencing in-house in a matter of days. Here, an approach for 16S rRNA gene amplicon sequencing using a benchtop next-generation sequencer is detailed. The environmental DNA is first amplified by PCR using primers that contain sequencing adapters and barcodes. They are then coupled to spherical particles via emulsion PCR. The particles are loaded on a disposable chip and the chip is inserted in the sequencing machine after which the sequencing is performed. The sequences are retrieved in fastq format, filtered and the barcodes are used to establish the sample membership of the reads. The filtered and binned reads are then further analyzed using publically available tools. An example analysis where the reads were classified with a taxonomy-finding algorithm within the software package Mothur is given. The method outlined here is simple, inexpensive and straightforward and should help smaller labs to take advantage from the ongoing genomic revolution.

Characterizing microbial community has been a longstanding goal in environmental microbiology. Next-generation sequencing methods now allow for the characterization of microbial communities at an unprecedented depth with minimal cost and labor. We detail here our approach to sequence bacterial 16S ribosomal RNA genes using a benchtop sequencer.

One of the major questions in microbial ecology is &#8220;who is there?&#8221; This question can be answered using various tools, but one of the ...

Targeted DNA Methylation Analysis by Next-generation Sequencing

The role of epigenetic processes in the control of gene expression has been known for a number of years. DNA methylation at cytosine residues is of particular interest for epigenetic studies as it has been demonstrated to be both a long lasting and a dynamic regulator of gene expression. Efforts to examine epigenetic changes in health and disease have been hindered by the lack of high-throughput, quantitatively accurate methods. With the advent and popularization of next-generation sequencing (NGS) technologies, these tools are now being applied to epigenomics in addition to existing genomic and transcriptomic methodologies. For epigenetic investigations of cytosine methylation where regions of interest, such as specific gene promoters or CpG islands, have been identified and there is a need to examine significant numbers of samples with high quantitative accuracy, we have developed a method called Bisulfite Amplicon Sequencing (BSAS). This method combines bisulfite conversion with targeted amplification of regions of interest, transposome-mediated library construction and benchtop NGS. BSAS offers a rapid and efficient method for analysis of up to 10 kb of targeted regions in up to 96 samples at a time that can be performed by most research groups with basic molecular biology skills. The results provide absolute quantitation of cytosine methylation with base specificity. BSAS can be applied to any genomic region from any DNA source. This method is useful for hypothesis testing studies of target regions of interest as well as confirmation of regions identified in genome-wide methylation analyses such as whole genome bisulfite sequencing, reduced representation bisulfite sequencing, and methylated DNA immunoprecipitation sequencing.

Bisulfite amplicon sequencing (BSAS) is a method for quantifying cytosine methylation in targeted genomic regions of interest. This method uses bisulfite conversion paired with PCR amplification of target regions prior to next-generation sequencing to produce absolute quantitation of DNA methylation at a base-specific level.

The role of epigenetic processes in the control of gene expression has been known for a number of years. DNA methylation at cytosine residues is of ...

Amplification, Next-generation Sequencing, and Genomic DNA Mapping of Retroviral Integration Sites

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of diverse libraries of retroviral integration sites using ligation-mediated PCR (LM-PCR) amplification and next-generation sequencing (NGS), (2) mapping the genomic location of each virus-host junction using BEDTools, and (3) analyzing the data for statistical relevance. Genomic DNA extracted from infected cells is fragmented by digestion with restriction enzymes or by sonication. After suitable DNA end-repair, double-stranded linkers are ligated onto the DNA ends, and semi-nested PCR is conducted using primers complementary to both the long terminal repeat (LTR) end of the virus and the ligated linker DNA. The PCR primers carry sequences required for DNA clustering during NGS, negating the requirement for separate adapter ligation. Quality control (QC) is conducted to assess DNA fragment size distribution and adapter DNA incorporation prior to NGS. Sequence output files are filtered for LTR-containing reads, and the sequences defining the LTR and the linker are cropped away. Trimmed host cell sequences are mapped to a reference genome using BLAT and are filtered for minimally 97% identity to a unique point in the reference genome. Unique integration sites are scrutinized for adjacent nucleotide (nt) sequence and distribution relative to various genomic features. Using this protocol, integration site libraries of high complexity can be constructed from genomic DNA in three days. The entire protocol that encompasses exogenous viral infection of susceptible tissue culture cells to integration site analysis can therefore be conducted in approximately one to two weeks. Recent applications of this technology pertain to longitudinal analysis of integration sites from HIV-infected patients.

We describe a protocol for amplifying retroviral integration sites from the genomic DNA of infected cells, sequencing the amplified virus-host junctions, and then mapping these sequences to a reference genome. We also describe techniques to quantify the distribution of integration sites relative to various genomic annotations using BEDTools.

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of ...

Efficient Nucleic Acid Extraction and 16S rRNA Gene Sequencing for Bacterial Community Characterization

There is a growing appreciation for the role of microbial communities as critical modulators of human health and disease. High throughput sequencing technologies have allowed for the rapid and efficient characterization of bacterial communities using 16S rRNA gene sequencing from a variety of sources. Although readily available tools for 16S rRNA sequence analysis have standardized computational workflows, sample processing for DNA extraction remains a continued source of variability across studies. Here we describe an efficient, robust, and cost effective method for extracting nucleic acid from swabs. We also delineate downstream methods for 16S rRNA gene sequencing, including generation of sequencing libraries, data quality control, and sequence analysis. The workflow can accommodate multiple samples types, including stool and swabs collected from a variety of anatomical locations and host species. Additionally, recovered DNA and RNA can be separated and used for other applications, including whole genome sequencing or RNA-seq. The method described allows for a common processing approach for multiple sample types and accommodates downstream analysis of genomic, metagenomic and transcriptional information.

We describe an efficient, robust, and cost effective method for extracting nucleic acid from swabs for characterization of bacterial communities using 16S rRNA gene amplicon sequencing. The method allows for a common processing approach for multiple sample types and accommodates a number of downstream analytic processes.

There is a growing appreciation for the role of microbial communities as critical modulators of human health and disease. High throughput sequencing ...

Guided Protocol for Fecal Microbial Characterization by 16S rRNA-Amplicon Sequencing

The human intestinal microbiome plays a central role in protecting cells from injury, in processing energy and nutrients, and in promoting immunity. Deviations from what is considered a healthy microbiota composition (dysbiosis) may impair vital functions leading to pathologic conditions. Recent and ongoing research efforts have been directed toward the characterization of associations between microbial composition and human health and disease.
Advances in high-throughput sequencing technologies enable characterization of the gut microbial composition. These methods include 16S rRNA-amplicon sequencing and shotgun sequencing. 16S rRNA-amplicon sequencing is used to profile taxonomical composition, while shotgun sequencing provides additional information about gene predictions and functional annotation. An advantage in using a targeted sequencing method of the 16S rRNA gene variable region is its substantially lower cost compared to shotgun sequencing. Sequence differences in the 16S rRNA gene are used as a microbial fingerprint to identify and quantify different taxa within an individual sample.
Major international efforts have enlisted standards for 16S rRNA-amplicon sequencing. However, several studies report a common source of variation caused by batch effect. To minimize this effect, uniformed protocols for sample collection, processing, and sequencing must be implemented. This protocol proposes the integration of broadly used protocols starting from fecal sample collection to data analyses. This protocol includes a column-free, direct-PCR approach that enables simultaneous handling and DNA extraction of large numbers of fecal samples, along with PCR amplification of the V4 region. In addition, the protocol describes the analysis pipeline and provides a script using the latest version of QIIME (QIIME 2 version 2017.7.0 and DADA2). This step-by-step protocol is aimed to guide those interested in initiating the use of 16S rRNA-amplicon sequencing in a robust, reproductive, easy to use, detailed way.

This manuscript describes a detailed standardized protocol of high-throughput 16S rRNA-amplicon sequencing. The protocol introduces an integrated, uniformed, feasible, and inexpensive protocol starting from fecal sample collection through data analyses. This protocol enables analysis of large numbers of samples with rigorous standards and several controls.

The human intestinal microbiome plays a central role in protecting cells from injury, in processing energy and nutrients, and in promoting immunity. ...

Interactome-Seq: A Protocol for Domainome Library Construction, Validation and Selection by Phage Display and Next Generation Sequencing

Folding reporters are proteins with easily identifiable phenotypes, such as antibiotic resistance, whose folding and function is compromised when fused to poorly folding proteins or random open reading frames. We have developed a strategy where, by using TEM-1 &#946;-lactamase (the enzyme conferring ampicillin resistance) on a genomic scale, we can select collections of correctly folded protein domains from the coding portion of the DNA of any intronless genome. The protein fragments obtained by this approach, the so called &#34;domainome&#34;, will be well expressed and soluble, making them suitable for structural/functional studies.
By cloning and displaying the &#34;domainome&#34; directly in a phage display system, we have showed that it is possible to select specific protein domains with the desired binding properties (e.g., to other proteins or to antibodies), thus providing essential experimental information for gene annotation or antigen identification.
The identification of the most enriched clones in a selected polyclonal population can be achieved by using novel next-generation sequencing technologies (NGS). For these reasons, we introduce deep sequencing analysis of the library itself and the selection outputs to provide complete information on diversity, abundance and precise mapping of each of the selected fragment. The protocols presented here show the key steps for library construction, characterization, and validation.

The protocols described allow the construction, characterization and selection (against the target of choice) of a &#34;domainome&#34; library made from any DNA source. This is achieved by a research pipeline that combines different technologies: phage display, a folding reporter and next generation sequencing with a web tool for data analysis.

Folding reporters are proteins with easily identifiable phenotypes, such as antibiotic resistance, whose folding and function is compromised when fused to ...

Tick Microbiome Characterization by Next-Generation 16S rRNA Amplicon Sequencing

In recent decades, vector-borne diseases have re-emerged and expanded at alarming rates, causing considerable morbidity and mortality worldwide. Effective and widely available vaccines are lacking for a majority of these diseases, necessitating the development of novel disease mitigation strategies. To this end, a promising avenue of disease control involves targeting the vector microbiome, the community of microbes inhabiting the vector. The vector microbiome plays a pivotal role in pathogen dynamics, and manipulations of the microbiome have led to reduced vector abundance or pathogen transmission for a handful of vector-borne diseases. However, translating these findings into disease control applications requires a thorough understanding of vector microbial ecology, historically limited by insufficient technology in this field. The advent of next-generation sequencing approaches has enabled rapid, highly parallel sequencing of diverse microbial communities. Targeting the highly-conserved 16S rRNA gene has facilitated characterizations of microbes present within vectors under varying ecological and experimental conditions. This technique involves amplification of the 16S rRNA gene, sample barcoding via PCR, loading samples onto a flow cell for sequencing, and bioinformatics approaches to match sequence data with phylogenetic information. Species or genus-level identification for a high number of replicates can typically be achieved through this approach, thus circumventing challenges of low detection, resolution, and output from traditional culturing, microscopy, or histological staining techniques. Therefore, this method is well-suited for characterizing vector microbes under diverse conditions but cannot currently provide information on microbial function, location within the vector, or response to antibiotic treatment. Overall, 16S next-generation sequencing is a powerful technique for better understanding the identity and role of vector microbes in disease dynamics.

Here we present a next-generation sequencing protocol for 16S rRNA sequencing which enables identification and characterization of microbial communities within vectors. This method involves DNA extraction, amplification and barcoding of samples through PCR, sequencing on a flow-cell, and bioinformatics to match sequence data to phylogenetic information.

In recent decades, vector-borne diseases have re-emerged and expanded at alarming rates, causing considerable morbidity and mortality worldwide. Effective ...

Two-Step Reverse Transcription Droplet Digital PCR Protocols for SARS-CoV-2 Detection and Quantification

Diagnosis of the ongoing SARS-CoV-2 pandemic is a priority for all countries across the globe. Currently, reverse transcription quantitative PCR (RT-qPCR) is the gold standard for SARS-CoV-2 diagnosis as no permanent solution is available. However effective this technique may be, research has emerged showing its limitations in detection and diagnosis especially when it comes to low abundant targets. In contrast, droplet digital PCR (ddPCR), a recent emerging technology with superior advantages over qPCR, has been shown to overcome the challenges of RT-qPCR in diagnosis of SARS-CoV-2 from low abundant target samples. Prospectively, in this article, the capabilities of RT-ddPCR are further expanded by showing steps on how to develop simplex, duplex, triplex probe mix, and quadruplex assays using a two-color detection system. Using primers and probes targeting specific sites of the SARS-CoV-2 genome (N, ORF1ab, RPP30, and RBD2), the development of these assays is shown to be possible. Additionally, step by step detailed protocols, notes, and suggestions on how to improve the assays workflow and analyze data are provided. Adapting this workflow in future works will ensure that the maximum number of targets can be sensitively detected in a small sample significantly improving on cost and sample throughput.

This work summarizes steps on developing different assays for SARS-CoV-2 detection using a two color ddPCR system. The steps are elaborate and notes have been included on how to improve the assays and experiment performance. These assays may be used for multiple SARS-CoV-2 RT-ddPCR applications.

Diagnosis of the ongoing SARS-CoV-2 pandemic is a priority for all countries across the globe. Currently, reverse transcription quantitative PCR (RT-qPCR) ...

A Magnetic-Bead-Based Mosquito DNA Extraction Protocol for Next-Generation Sequencing

A recently published DNA extraction protocol using magnetic beads and an automated DNA extraction instrument suggested that it is possible to extract high quality and quantity DNA from a well-preserved individual mosquito sufficient for downstream whole genome sequencing. However, reliance on an expensive automated DNA extraction instrument can be prohibitive for many laboratories. Here, the study provides a budget-friendly magnetic-bead-based DNA extraction protocol, which is suitable for low to medium throughput. The protocol described here was successfully tested using individual Aedes aegypti mosquito samples. The reduced costs associated with high quality DNA extraction will increase the application of high throughput sequencing to resource limited labs and studies.

Described here is a DNA extraction protocol using magnetic beads to produce high quality DNA extractions from mosquitoes. These extractions are suitable for a downstream next-generation sequencing approach.

A recently published DNA extraction protocol using magnetic beads and an automated DNA extraction instrument suggested that it is possible to extract high ...