Phase Genomics recently launched its ProxiMeta™ Hi-C metagenome deconvolution kit+software
product, enabling researchers to bring this powerful technology (previously only available through the ProxiMeta service) into their own labs. A new paper posted to biorxiv describes the results of employing ProxiMeta technology to deconvolute a human gut microbiome sample.
In the paper, ProxiMeta was used on a single human gut microbiome sample and isolated 252 individual microbial genomes or genome fragments, with 50 of these genomes meeting the “near-complete” threshold typically used as the standard according to the CheckM tool (>90% complete, <10% contaminated). Examining the tRNA and rRNA content of the genomes found 10 to meet “high-quality” and 75 to meet “medium-quality” thresholds. Additionally, 14 of the genomes represent near-complete assemblies of novel species or strains not found in RefSeq, showing that even after many years of research, there remain numerous unknown microbes in the human gut that are discoverable with new approaches.
ProxiMeta’s results were compared to those achieved with MaxBin, a common tool used to perform metagenomic binning based on heuristics such as shotgun read depth and tetranucleotide profiles. MaxBin was able to create 29 near-complete genomes (cf. 50 for ProxiMeta), with only 5 meeting high-quality (cf. 10) and 44 meeting medium-quality (cf. 75) thresholds based on tRNA and rRNA content. In terms of ability to construct similar sets of near-complete genomes, ProxiMeta and MaxBin constructed 27 of approximately the same genomes, with ProxiMeta constructing an additional 32 genomes that MaxBin did not, and MaxBin constructing 9 genomes that ProxiMeta did not. ProxiMeta’s assembled genomes also exhibited a much lower amount of contamination than MaxBin’s assembled genomes, with 43% of MaxBin’s assemblies exceeding the 10% contamination limit that is the typical standard for genome quality, compared to only 2% of ProxiMeta’s assemblies.
Other results unique to ProxiMeta include the discovery of near-complete genomes for 14 novel species or strains and various associations of plasmids with their hosts. Of the 14 novel genomes, 10 appear to be of the class Clostridia, a common group of gut microbes that are poorly characterized due to their difficulty to culture. ProxiMeta also assigned 137 contigs containing plasmid content to a cluster and identified candidate plasmid sequences as being present across multiple, distantly related bacteria. For example, ProxiMeta placed a known megaplasmid into an assembly for Eubacterium eligens that included homologous plasmid sequences placed into several other genomes, suggesting either the presence of the megaplasmid into other species, or variants of the megaplasmid being found on other mobile elements spread through the metagenome.
The depth of the resulting data and results offers the opportunity to learn much more about this microbial niche and research continues to unlock new discoveries about this community. Phase Genomics is thrilled to be able to offer all researchers the same new power to dig deeper into their mixed samples than ever before, especially now with a product that puts the power of discovery in their hands.
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