Development of quantitative PCR (QPCR) assays typically requires extensive screening within and across a given species to ensure specific detection and lucid identification among various pathogenic ...and nonpathogenic strains and to generate standard curves. To minimize screening requirements, multiple virulence and marker genes (VMGs) were targeted simultaneously to enhance reliability, and a predictive threshold cycle (CT) equation was developed to calculate the number of starting copies based on an experimental CT. The empirical equation was developed with Sybr green detection in nanoliter-volume QPCR chambers (OpenArray) and tested with 220 previously unvalidated primer pairs targeting 200 VMGs from 30 pathogens. A high correlation (R² = 0.816) was observed between the predicted and experimental CTs based on the organism's genome size, guanine and cytosine (GC) content, amplicon length, and stability of the primer's 3' end. The performance of the predictive CT equation was tested using 36 validation samples consisting of pathogenic organisms spiked into genomic DNA extracted from three environmental waters. In addition, the primer success rate was dependent on the GC content of the target organisms and primer sequences. Targeting multiple assays per organism and using the predictive CT equation are expected to reduce the extent of the validation necessary when developing QPCR arrays for a large number of pathogens or other targets.
Rapid, sensitive, and low-cost pathogen diagnostic systems are needed for early disease diagnosis and treatment, especially in resource-limited settings. This study reports a low-cost charge-coupled ...device (CCD)-based fluorescence imaging system for rapid detection of waterborne pathogens by isothermal gene amplification in disposable microchips. Fluorescence imaging capability of this monochromatic CCD camera is evaluated by optimizing the gain, offset, and exposure time. This imaging system is validated for 12 virulence genes of major waterborne pathogens on cyclic olefin polymer (COP) microchips, using SYTO-82 dye and real time fluorescence loop-mediated isothermal amplification referred here as microRT
f
-LAMP. Signal-to-noise ratio (SNR) and threshold time (Tt) of microRT
f
-LAMP assays are compared with those from a commercial real-time polymerase chain reaction (PCR) instrument. Applying a CCD exposure of 5 s to 10
5
starting DNA copies of microRT
f
-LAMP assays increases the SNR by 8-fold and reduces the Tt by 9.8 min in comparison to a commercial real-time PCR instrument. Additionally, single copy level sensitivity for
Campylobacter jejuni
0414 gene is obtained for microRT
f
-LAMP with a Tt of 19 min, which is half the time of the commercial real-time PCR instrument. Due to the control over the exposure time and the wide field imaging capability of CCD, this low-cost fluorescence imaging system has the potential for rapid and parallel detection of pathogenic microorganisms in high throughput microfluidic chips.
Certain symptoms associated with mild sickness and lethargy have not been categorized as definitive diseases. Confirming such symptoms in captive monkeys (Macaca fascicularis, known as cynomolgus ...monkeys) can be difficult; however, it is possible to observe and analyze their feces. In this study, we investigated the relationship between stool state and various omics data by considering objective and quantitative values of stool water content as a phenotype for analysis. By examining the food intake of the monkeys and assessing their stool, urine, and plasma, we attempted to obtain a comprehensive understanding of the health status of individual monkeys and correlate it with the stool condition. Our metabolomics data strongly suggested that many lipid-related metabolites were correlated with the stool water content. The lipidomic analysis revealed the involvement of saturated and oxidized fatty acids, metallomics revealed the contribution of selenium (a bio-essential trace element), and intestinal microbiota analysis revealed the association of several bacterial species with the stool water content. Based on our results, we hypothesize that the redox imbalance causes minor health problems. However, it is not possible to make a definite conclusion using multi-omics alone, and other hypotheses could be proposed.
Standardization and quality assurance of microbiome community analysis by high-throughput DNA sequencing require widely accessible and well-characterized reference materials. Here, we report on newly ...developed DNA and whole-cell mock communities to serve as control reagents for human gut microbiota measurements by shotgun metagenomics and 16S rRNA gene amplicon sequencing. The mock communities were formulated as near-even blends of up to 20 bacterial species prevalent in the human gut, span a wide range of genomic guanine-cytosine (GC) contents, and include multiple strains with Gram-positive type cell walls. Through a collaborative study, we carefully characterized the mock communities by shotgun metagenomics, using previously developed standardized protocols for DNA extraction and sequencing library construction. Further, we validated fitness of the mock communities for revealing technically meaningful differences among protocols for DNA extraction and metagenome/16S rRNA gene amplicon library construction. Finally, we used the mock communities to reveal varying performance of metagenome-based taxonomic profilers and the impact of trimming and filtering of sequencing reads on observed species profiles. The latter showed that aggressive preprocessing of reads may result in substantial GC-dependent bias and should thus be carefully evaluated to minimize unintended effects on species abundances. Taken together, the mock communities are expected to support a myriad of applications that rely on well-characterized control reagents, ranging from evaluation and optimization of methods to assessment of reproducibility in interlaboratory studies and routine quality control.
Application of high-throughput DNA sequencing has greatly accelerated human microbiome research and its translation into new therapeutic and diagnostic capabilities. Microbiome community analyses results can, however, vary considerably across studies or laboratories, and establishment of measurement standards to improve accuracy and reproducibility has become a priority. The here-developed mock communities, which are available from the NITE Biological Resource Center (NBRC) at the National Institute of Technology and Evaluation (NITE, Japan), provide well-characterized control reagents that allow users to judge the accuracy of their measurement results. Widespread and consistent adoption of the mock communities will improve reproducibility and comparability of microbiome community analyses, thereby supporting and accelerating human microbiome research and development.
Abstract
The goal of this study was to develop and validate a novel fosmid-clone-based metagenome isotope array approach — termed the community isotope array (CIArray) — for sensitive detection and ...identification of microorganisms assimilating a radiolabeled substrate within complex microbial communities. More specifically, a sample-specific CIArray was used to identify anoxic phenol-degrading microorganisms in activated sludge treating synthetic coke-oven wastewater in a single-sludge predenitrification–nitrification process. Hybridization of the CIArray with DNA from the 14C-phenol-amended sample indicated that bacteria assimilating 14C-atoms, presumably directly from phenol, under nitrate-reducing conditions were abundant in the reactor, and taxonomic assignment of the fosmid clone end sequences suggested that they belonged to the Gammaproteobacteria. The specificity of the CIArray was validated by quantification of fosmid-clone-specific DNA in density-resolved DNA fractions from samples incubated with 13C-phenol, which verified that all CIArray-positive probes stemmed from microorganisms that assimilated isotopically labeled carbon. This also demonstrated that the CIArray was more sensitive than DNA-SIP, as the former enabled positive detection at a phenol concentration that failed to yield a ‘heavy’ DNA fraction. Finally, two operational taxonomic units distantly related to marine Gammaproteobacteria were identified to account for more than half of 16S rRNA gene clones in the ‘heavy’ DNA library, corroborating the CIArray-based identification.
Parallel detection approaches are of interest to many researchers interested in identifying multiple water and foodborne pathogens simultaneously. Availability and cost-effectiveness are two key ...factors determining the usefulness of such approaches for laboratories with limited resources. In this study, we developed and validated a high-density microarray for simultaneous screening of 14 bacterial pathogens using an approach that employs gold labeling with silver enhancement (GLS) protocol. In total, 8887 probes (50-mer) were designed using an in-house database of virulence and marker genes (VMGs), and synthesized in quadruplicate on glass slides using an in-situ synthesis technology. Target VMG amplicons were obtained using multiplex polymerase chain reaction (PCR), labeled with biotin, and hybridized to the microarray. The signals generated after gold deposition and silver enhancement, were quantified using a flatbed scanner having 2-μm resolution. Data analysis indicated that reliable presence/absence calls could be made, if: i) over four probes were used per gene, ii) the signal-to-noise ratio (SNR) cutoff was greater than or equal to two, and iii) the positive fraction (PF), i.e., number of probes with SNR≥2 for a given VMG was greater than 0.75. Hybridization of the array with blind samples resulted in 100% correct calls, and no false positive. Because amplicons were obtained by multiplex PCR, sensitivity of this method is similar to PCR. This assay is an inexpensive and reliable technique for high throughput screening of multiple pathogens.
•A gold-silver labeling technique was validated for the presence of 14 pathogens.•The labeling method allows use of a low cost flatbed scanner for presence/absence.•The method is extendable to detection of other pathogens in limited resource settings.•Hybridization of the 8000 probe array with blind samples resulted in 100% correct calls.
Pathogen detection tools with high reliability are needed for various applications, including food and water safety and clinical diagnostics. In this study, we designed and validated an in ...situ-synthesized biochip for detection of 12 microbial pathogens, including a suite of pathogens relevant to water safety. To enhance the reliability of presence/absence calls, probes were designed for multiple virulence and marker genes (VMGs) of each pathogen, and each VMG was targeted by an average of 17 probes. Hybridization of the biochip with amplicon mixtures demonstrated that 95% of the initially designed probes behaved as predicted in terms of positive/negative signals. The probes were further validated using DNA obtained from three different types of water samples and spiked with pathogen genomic DNA at decreasing relative abundance. Excellent specificity for making presence/absence calls was observed by using a cutoff of 0.5 for the positive fraction (i.e., the fraction of probes yielding a positive signal for a given VMG). A split multiplex PCR design for simultaneous amplification of the VMGs resulted in a detection limit of between 0.1 and 0.01% relative abundance, depending on the type of pathogen and the VMG. Thermodynamic analysis of the hybridization patterns obtained with DNA from the different water samples demonstrated that probes with a hybridization Gibbs free energy of approximately -19.3 kcal/mol provided the best trade-off between sensitivity and specificity. The developed biochip may be used to detect the described bacterial pathogens in water samples when parallel and specific detection is required.
We announce the complete genome sequence of
Megamonas funiformis
JCM 14723
T
(YIT 11815
T
). The genome consists of a circular chromosome (2,522,577 bp, 31.5% G+C content) and a plasmid of 46,189 bp ...(29.4% G+C content). The genome was predicted to contain 6 rRNA operons, 53 tRNA genes, and 2,440 protein-coding sequences.
We announce the complete genome sequence of
Megamonas funiformis
JCM 14723
T
(YIT 11815
T
). The genome consists of a circular chromosome (2,522,577 bp, 31.5% G+C content) and a plasmid of 46,189 bp (29.4% G+C content). The genome was predicted to contain 6 rRNA operons, 53 tRNA genes, and 2,440 protein-coding sequences.
We report here a high-quality draft genome sequence of
strain NM-5
, a facultative anaerobic, mesophilic, fermentative bacterium belonging to the class
of the phylum
The genome comprises 4,751,807 bp ...in three contigs and has a G+C content of 60.19%. Annotation predicted 4,175 protein-coding sequences and 54 RNAs.
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