Dataset Information

Optimizing microbiome sequencing for small intestinal aspirates: validation of novel techniques through the REIMAGINE study.

ABSTRACT:

Background

The human small intestine plays a central role in the processes of digestion and nutrient absorption. However, characterizations of the human gut microbiome have largely relied on stool samples, and the associated methodologies are ill-suited for the viscosity and low microbial biomass of small intestine samples. As part of the REIMAGINE study to examine the specific roles of the small bowel microbiome in human health and disease, this study aimed to develop and validate methodologies to optimize microbial analysis of the small intestine.

Results

Subjects undergoing esophagogastroduodenoscopy without colon preparation for standard of care were prospectively recruited, and ~?2?ml samples of luminal fluid were obtained from the duodenum using a custom sterile aspiration catheter. Samples of duodenal aspirates were either untreated (DA-U, N =?127) or pretreated with dithiothreitol (DA-DTT, N =?101), then cultured on MacConkey agar for quantitation of aerobic gram-negative bacteria, typically from the class Gammaproteobacteria, and on blood agar for quantitation of anaerobic microorganisms. DA-DTT exhibited 2.86-fold greater anaerobic bacterial counts compared to DA-U (P =?0.0101), but were not statistically different on MacConkey agar. DNA isolation from DA-U (N =?112) and DA-DTT (N =?43) samples and library preparation for 16S rRNA gene sequencing were also performed using modified protocols. DA-DTT samples exhibited 3.81-fold higher DNA concentrations (P =?0.0014) and 4.18-fold higher 16S library concentrations (P ConclusionsThis study validates novel DTT-based methodology which optimizes microbial culture and 16S rRNA gene sequencing for the study of the small bowel microbiome. The microbial analyses indicate increased isolation of facultative and obligate anaerobes from the mucus layer using these novel techniques.

SUBMITTER: Leite GGS

PROVIDER: S-EPMC6824053 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Publications

Optimizing microbiome sequencing for small intestinal aspirates: validation of novel techniques through the REIMAGINE study.

Leite Gabriela Guimaraes Sousa GGS Morales Walter W Weitsman Stacy S Celly Shreya S Parodi Gonzalo G Mathur Ruchi R Sedighi Rashin R Barlow Gillian M GM Rezaie Ali A Pimentel Mark M

BMC microbiology 20191101 1

<h4>Background</h4>The human small intestine plays a central role in the processes of digestion and nutrient absorption. However, characterizations of the human gut microbiome have largely relied on stool samples, and the associated methodologies are ill-suited for the viscosity and low microbial biomass of small intestine samples. As part of the REIMAGINE study to examine the specific roles of the small bowel microbiome in human health and disease, this study aimed to develop and validate metho ...[more]

PMID: 31675917

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Project description:BackgroundThe intestinal microbiota plays a crucial role in protecting the host from pathogenic microbes, modulating immunity and regulating metabolic processes. We studied the simplified human intestinal microbiota (SIHUMIx) consisting of eight bacterial species with a particular focus on the discovery of novel small proteins with less than 100 amino acids (= sProteins), some of which may contribute to shape the simplified human intestinal microbiota. Although sProteins carry out a wide range of important functions, they are still often missed in genome annotations, and little is known about their structure and function in individual microbes and especially in microbial communities.ResultsWe created a multi-species integrated proteogenomics search database (iPtgxDB) to enable a comprehensive identification of novel sProteins. Six of the eight SIHUMIx species, for which no complete genomes were available, were sequenced and de novo assembled. Several proteomics approaches including two earlier optimized sProtein enrichment strategies were applied to specifically increase the chances for novel sProtein discovery. The search of tandem mass spectrometry (MS/MS) data against the multi-species iPtgxDB enabled the identification of 31 novel sProteins, of which the expression of 30 was supported by metatranscriptomics data. Using synthetic peptides, we were able to validate the expression of 25 novel sProteins. The comparison of sProtein expression in each single strain versus a multi-species community cultivation showed that six of these sProteins were only identified in the SIHUMIx community indicating a potentially important role of sProteins in the organization of microbial communities. Two of these novel sProteins have a potential antimicrobial function. Metabolic modelling revealed that a third sProtein is located in a genomic region encoding several enzymes relevant for the community metabolism within SIHUMIx.ConclusionsWe outline an integrated experimental and bioinformatics workflow for the discovery of novel sProteins in a simplified intestinal model system that can be generically applied to other microbial communities. The further analysis of novel sProteins uniquely expressed in the SIHUMIx multi-species community is expected to enable new insights into the role of sProteins on the functionality of bacterial communities such as those of the human intestinal tract. Video abstract.

Project description:Small intestinal bacterial overgrowth (SIBO) is highly prevalent and is associated with numerous gastrointestinal disorders, but the microbes involved remain poorly defined. Moreover, existing studies of microbiome alterations in SIBO have utilized stool samples, which are not representative of the entire gastrointestinal tract. Therefore, we aimed to determine and compare the duodenal microbiome composition in SIBO and non-SIBO subjects, using duodenal aspirates from subjects undergoing standard-of-care esophagogastroduodenoscopy without colon preparation. Using the recently-redefined cutoff for SIBO of >103 colony forming units per milliliter (CFU/mL), 42 SIBO and 98 non-SIBO subjects were identified. Duodenal samples from SIBO subjects had 4x103-fold higher counts than non-SIBO subjects when plated on MacConkey agar (P<0.0001), and 3.8-fold higher counts when plated on blood agar (P<0.0001). Twenty subjects had also undergone lactulose hydrogen breath tests (LHBTs), of whom 7/20 had SIBO. At the 90-minute timepoint, 4/7 SIBO subjects had positive LHBTs (rise in hydrogen (H2) ??20 ppm above baseline), as compared to 2/13 non-SIBO subjects. 16S ribosomal RNA (rRNA) sequencing revealed that SIBO subjects had 4.31-fold higher relative abundance of Proteobacteria (FDR P<0.0001) and 1.64-fold lower Firmicutes (P<0.0003) than non-SIBO subjects. This increased relative abundance of Proteobacteria correlated with decreased ?-diversity in SIBO subjects (Spearman R = 0.4866, P<0.0001) Specific increases in class Gammaproteobacteria correlated with the area-under-the-curve for H2 for 0-90 mins during LHBT (R = 0.630, P = 0.002). Increases in Gammaproteobacteria resulted primarily from higher relative abundances of the family Enterobacteriaceae (FDR P<0.0001), which correlated with the symptom of bloating (Spearman R = 0.185, 2-tailed P = 0.028). Increases in family Aeromonadaceae correlated with urgency with bowel movement (Spearman R = 0.186, 2-tailed P = 0.028). These results validate the >103 CFU/mL cutoff for the definition of SIBO, and also reveal specific overgrowth of Proteobacteria in SIBO vs. non-SIBO subjects, coupled with an altered Proteobacterial profile that correlates with symptom severity. Future research may elucidate host-microbiome interactions underlying these symptoms in SIBO patients.

Project description:The intestinal microbiota plays a crucial role in protecting the host from pathogenic microbes, in modulating immunity and in regulating metabolic processes. We use the simplified human intestinal microbiota (SIHUMIx) consisting of eight bacterial species to study potential synergistic effects with a particular focus on detecting novel proteins with less than 100 amino acids (= sProteins), some of which may contribute to regulate the simplified human intestinal microbiota. Although several studies have shown that sProteins carry out a wide range of important functions, they are still often missed in genome annotations, and little is known about their structure and function in individual microbes and especially in microbial communities. In this study, we created a multi-species integrated proteogenomics search database (multi-species iPtgxDB) to enable a comprehensive identification of novel sProteins. Six of the eight SIHUMIx species, for which no complete genomes were available, were first sequenced and de novo assembled. Several proteomics approaches including two earlier optimized sProtein enrichment strategies were applied prior to mass spectrometric analysis to specifically increase the chances for novel sProtein discovery. Searching the MS/MS data against the multi-species iPtgxDB enabled us to identify 31 novel sProteins, of which the expression of 30 was supported by metatranscriptomics data. Using synthetic peptides, we were able to validate the expression of 25 novel sProteins. Importantly, when comparing the expression of these novel sProteins in single strain cultivations to the multi-species community grown in a bioreactor, we found that six of them were only identified in the SIHUMIx community, indicating a possible important role of sProteins in the organization of microbial communities. Furthermore, in silico prediction suggested that two of these novel sProteins have a potential antimicrobial function. We outline an integrated experimental and bioinformatics workflow for the discovery of novel sProteins in microbial communities that can be generically applied to other microbial communities. The further analysis of novel sProteins uniquely expressed in the multi-species community is expected to enable new insights into the structure, regulation and function of bacterial communities such as those of the human intestinal tract.

Project description:BackgroundThe cervicovaginal microbiome (CVM) plays a significant role in women's cervical health and disease. Microbial alterations at the species level and characteristic community state types (CST) have been associated with acquisition and persistence of high-risk human papillomavirus (hrHPV) infections that may result in progression of cervical lesions to malignancy. Current sequencing methods, especially most commonly used multiplex 16S rRNA gene sequencing, struggle to fully clarify these changes because they generally fail to provide sufficient taxonomic resolution to adequately perform species-level associative studies. To improve CVM species designation, we designed a novel sequencing tool targeting microbes at the species taxonomic rank and examined its potential for profiling the CVM.ResultsWe introduce an accessible and practical circular probe-based RNA sequencing (CiRNAseq) technology with the potential to profile and quantify the CVM. In vitro and in silico validations demonstrate that CiRNAseq can distinctively detect species in a mock mixed microbial environment, with the output data reflecting its ability to estimate microbes' abundance. Moreover, compared to 16S rRNA gene sequencing, CiRNAseq provides equivalent results but with improved sequencing sensitivity. Analyses of a cohort of cervical smears from hrHPV-negative women versus hrHPV-positive women with high-grade cervical intraepithelial neoplasia confirmed known differences in CST occurring in the CVM of women with hrHPV-induced lesions. The technique also revealed variations in microbial diversity and abundance in the CVM of hrHPV-positive women when compared to hrHPV-negative women.ConclusionsCiRNAseq is a promising tool for studying the interplay between the CVM and hrHPV in cervical carcinogenesis. This technology could provide a better understanding of cervicovaginal CST and microbial species during health and disease, prompting the discovery of biomarkers, additional to hrHPV, that can help detect high-grade cervical lesions.

Dataset Information

Optimizing microbiome sequencing for small intestinal aspirates: validation of novel techniques through the REIMAGINE study.

Background

Results

Publications

Optimizing microbiome sequencing for small intestinal aspirates: validation of novel techniques through the REIMAGINE study.

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