Abstract
Long-read metagenome assembly promises complete genomic recovery from microbiomes. However, the complexity of metagenomes poses challenges. Here we present myloasm, a metagenome assembler for modern long reads such as PacBio HiFi and Oxford Nanopore Technologies (ONT) R10.4 long reads. Myloasm uses polymorphic k-mers to construct a high-resolution string graph and then leverages differential abundance for graph simplification. On real-world ONT metagenomes, myloasm assembled three times more complete circular contigs than the next-best assembler. Myloasm can make ONT and HiFi assemblies comparable. For example, on a jointly sequenced gut metagenome, myloasm with ONT assembled more complete circular genomes than any assembler with HiFi. Myloasm also recovers previously inaccessible within-species diversity. Here, we recovered six complete Prevotella copri single-contig genomes from a gut metagenome and eight complete TM7 (Saccharibacteria) contigs with >93% similarity from an oral metagenome. Overall, we show that myloasm outperforms existing long-read metagenome assemblers across a range of environments and modern sequencing technologies.
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Data availability
The mock nanopore community was generated from the MicroBench116 suite by R. Kirkegaard (https://github.com/Kirk3gaard/MicroBench and accession PRJEB85558) along with 14 isolates taken from ref. 37. Accessions for the mock communities are available in Supplementary Table 2. Accessions for the real metagenomic datasets are available in Supplementary Table 3. Source data are provided with this paper.
Code availability
Myloasm is open source and available at https://github.com/bluenote-1577/myloasm. Documentation for myloasm is available at https://myloasm-docs.github.io/. The mylotools software suite is open source and available at https://github.com/bluenote-1577/mylotools.
References
Quince, C., Walker, A. W., Simpson, J. T., Loman, N. J. & Segata, N. Shotgun metagenomics, from sampling to analysis. Nat. Biotechnol. 35, 833–844 (2017).
Hug, L. A. et al. A new view of the tree of life. Nat. Microbiol. 1, 1–6 (2016).
Parks, D. H. et al. Recovery of nearly 8,000 metagenome-assembled genomes substantially expands the tree of life. Nat. Microbiol. 2, 1533–1542 (2017).
Spang, A. et al. Complex archaea that bridge the gap between prokaryotes and eukaryotes. Nature 521, 173–179 (2015).
Zhao, S. et al. Adaptive evolution within gut microbiomes of healthy people. Cell Host Microbe 25, 656–667 (2019).
Pérez-Cobas, A. E., Gomez-Valero, L. & Buchrieser, C. Metagenomic approaches in microbial ecology: an update on whole-genome and marker gene sequencing analyses. Microb. Genom. 6, mgen000409 (2020).
Kiefl, E. et al. Structure-informed microbial population genetics elucidate selective pressures that shape protein evolution. Sci. Adv. 9, eabq4632 (2023).
Wallen, Z. D. et al. Metagenomics of Parkinson’s disease implicates the gut microbiome in multiple disease mechanisms. Nat. Commun. 13, 6958 (2022).
Tisza, M. J. & Buck, C. B. A catalog of tens of thousands of viruses from human metagenomes reveals hidden associations with chronic diseases. Proc. Natl Acad. Sci. USA 118, e2023202118 (2021).
Franzosa, E. A. et al. Gut microbiome structure and metabolic activity in inflammatory bowel disease. Nat. Microbiol. 4, 293–305 (2019).
Schmidt, T. S. B. et al. Drivers and determinants of strain dynamics following fecal microbiota transplantation. Nat. Med. 28, 1902–1912 (2022).
Bedarf, J. R. et al. Functional implications of microbial and viral gut metagenome changes in early stage L-DOPA-naïve Parkinson’s disease patients. Genome Med. 9, 39 (2017).
Woodcroft, B. J. et al. Genome-centric view of carbon processing in thawing permafrost. Nature 560, 49–54 (2018).
Ustick, L. J. et al. Metagenomic analysis reveals global-scale patterns of ocean nutrient limitation. Science 372, 287–291 (2021).
Liang, J.-L. et al. Novel phosphate-solubilizing bacteria enhance soil phosphorus cycling following ecological restoration of land degraded by mining. ISME J. 14, 1600–1613 (2020).
Cavicchioli, R. et al. Scientists’ warning to humanity: microorganisms and climate change. Nat. Rev. Microbiol. 17, 569–586 (2019).
Steen, A. D. et al. High proportions of bacteria and archaea across most biomes remain uncultured. ISME J. 13, 3126–3130 (2019).
Bertrand, D. et al. Hybrid metagenomic assembly enables high-resolution analysis of resistance determinants and mobile elements in human microbiomes. Nat. Biotechnol. 37, 937–944 (2019).
Kolmogorov, M. et al. metaFlye: scalable long-read metagenome assembly using repeat graphs. Nat. Methods 17, 1103–1110 (2020).
Benoit, G. et al. High-quality metagenome assembly from long accurate reads with metaMDBG. Nat. Biotechnol. 42, 1378–1383 (2024).
Feng, X., Cheng, H., Portik, D. & Li, H. Metagenome assembly of high-fidelity long reads with hifiasm-meta. Nat. Methods 19, 671–674 (2022).
Agustinho, D. P. et al. Unveiling microbial diversity: harnessing long-read sequencing technology. Nat. Methods 21, 954–966 (2024).
Feng, X. & Li, H. Evaluating and improving the representation of bacterial contents in long-read metagenome assemblies. Genome Biol. 25, 92 (2024).
Crits-Christoph, A., Olm, M. R., Diamond, S., Bouma-Gregson, K. & Banfield, J. F. Soil bacterial populations are shaped by recombination and gene-specific selection across a grassland meadow. ISME J. 14, 1834–1846 (2020).
Liu, Z. & Good, B. H. Dynamics of bacterial recombination in the human gut microbiome. PLOS Biol. 22, e3002472 (2024).
Chen-Liaw, A. et al. Gut microbiota strain richness is species specific and affects engraftment. Nature 637, 422–429 (2025).
Goyal, A., Bittleston, L. S., Leventhal, G. E., Lu, L. & Cordero, O. X. Interactions between strains govern the eco-evolutionary dynamics of microbial communities. eLife 11, e74987 (2022).
Brito, I. L. Examining horizontal gene transfer in microbial communities. Nat. Rev. Microbiol. 19, 442–453 (2021).
Nagarajan, N. & Pop, M. Parametric complexity of sequence assembly: theory and applications to next generation sequencing. J. Comput. Biol. 16, 897–908 (2009).
Bresler, G., Bresler, M. & Tse, D. Optimal assembly for high throughput shotgun sequencing. BMC Bioinformatics 14, S18 (2013).
Kerkvliet, J. J. et al. Metagenomic assembly is the main bottleneck in the identification of mobile genetic elements. PeerJ 12, e16695 (2024).
Nurk, S. et al. HiCanu: Accurate assembly of segmental duplications, satellites, and allelic variants from high-fidelity long reads. Genome Res. 30, 1291–1305 (2020).
Cheng, H., Concepcion, G. T., Feng, X., Zhang, H. & Li, H. Haplotype-resolved de novo assembly using phased assembly graphs with hifiasm. Nat. Methods 18, 170–175 (2021).
Minich, J. J. et al. Culture-independent meta-pangenomics enabled by long-read metagenomics reveals associations with pediatric undernutrition. Cell 188, 6666–6686 (2025).
Sereika, M. et al. Oxford Nanopore R10.4 long-read sequencing enables the generation of near-finished bacterial genomes from pure cultures and metagenomes without short-read or reference polishing. Nat. Methods 19, 823–826 (2022).
Cheng, H. et al. Efficient near-telomere-to-telomere assembly of nanopore simplex reads. Nature https://doi.org/10.1038/s41586-026-10105-6 (2026).
Hall, M. B. et al. Benchmarking reveals superiority of deep learning variant callers on bacterial nanopore sequence data. eLife 13, RP98300 (2024).
Myers, E. W. The fragment assembly string graph. Bioinformatics 21 Suppl 2, ii79–85 (2005).
Compeau, P. E. C., Pevzner, P. A. & Tesler, G. Why are de Bruijn graphs useful for genome assembly? Nat. Biotechnol. 29, 987–991 (2011).
Ekim, B., Berger, B. & Chikhi, R. Minimizer-space de Bruijn graphs: whole-genome assembly of long reads in minutes on a personal computer. Cell Syst. 12, 958–968 (2021).
Benoit, G. et al. High-quality metagenome assembly from nanopore reads with nanoMDBG. Nat. Commun. https://doi.org/10.1038/s41467-026-69760-y (2026).
Kirkpatrick, S., Gelatt, C. D. & Vecchi, M. P. Optimization by simulated annealing. Science 220, 671–680 (1983).
Trigodet, F., Sachdeva, R., Banfield, J. F. & Eren, A. M. Troubleshooting common errors in assemblies of long-read metagenomes. Nat. Biotechnol. https://doi.org/10.1038/s41587-025-02971-8 (2026).
Derelle, R. et al. Seamless, rapid and accurate analyses of outbreak genomic data using split k-mer analysis. Genome Res. 34, 1661–1673 (2024).
Gardner, S. N. & Hall, B. G. When whole-genome alignments just won’t work: kSNP v2 software for alignment-free SNP discovery and phylogenetics of hundreds of microbial genomes. PLoS ONE 8, e81760 (2013).
Harris, S. R. SKA: split kmer analysis toolkit for bacterial genomic epidemiology. Preprint at bioRxiv https://doi.org/10.1101/453142 (2018).
Edgar, R. Syncmers are more sensitive than minimizers for selecting conserved k-mers in biological sequences. PeerJ 9, e10805 (2021).
Myers, G. & Miller, W. Chaining multiple-alignment fragments in sub-quadratic time. In Proc. Sixth Annual ACM-SIAM Symposium on Discrete Algorithms (ed. Clarkson, K. L.) 38–47 (SIAM, 1995).
Li, H. Minimap2: pairwise alignment for nucleotide sequences. Bioinformatics 34, 3094–3100 (2018).
Li, H. Minimap and miniasm: fast mapping and de novo assembly for noisy long sequences. Bioinformatics 32, 2103–2110 (2016).
Bouras, G. et al. Hybracter: enabling scalable, automated, complete and accurate bacterial genome assemblies. Microb. Genom. 10, 001244 (2024).
Vaisbourd, E., Bren, A., Alon, U. & Glass, D. S. Preventing multimer formation in commonly used synthetic biology plasmids. ACS Synth. Biol. 14, 1309–1315 (2025).
Kiguchi, Y. et al. Giant extrachromosomal element ‘Inocle’ potentially expands the adaptive capacity of the human oral microbiome. Nat. Commun. 16, 7397 (2025).
Sereika, M. et al. Genome-resolved long-read sequencing expands known microbial diversity across terrestrial habitats. Nat. Microbiol. 10, 2018–2030 (2025).
Gehrig, J. L. et al. Finding the right fit: evaluation of short-read and long-read sequencing approaches to maximize the utility of clinical microbiome data. Microb. Genom. 8, 000794 (2022).
Sidhu, C. et al. Dissolved storage glycans shaped the community composition of abundant bacterioplankton clades during a North Sea spring phytoplankton bloom. Microbiome 11, 77 (2023).
Priest, T., Orellana, L. H., Huettel, B., Fuchs, B. M. & Amann, R. Microbial metagenome-assembled genomes of the Fram Strait from short and long read sequencing platforms. PeerJ 9, e11721 (2021).
Kato, S., Masuda, S., Shibata, A., Shirasu, K. & Ohkuma, M. Insights into ecological roles of uncultivated bacteria in Katase hot spring sediment from long-read metagenomics. Front. Microbiol. 13, 1045931 (2022).
Zhang, Y. et al. Improved microbial genomes and gene catalog of the chicken gut from metagenomic sequencing of high-fidelity long reads. Gigascience 11, giac116 (2022).
Chklovski, A., Parks, D. H., Woodcroft, B. J. & Tyson, G. W. CheckM2: a rapid, scalable and accurate tool for assessing microbial genome quality using machine learning. Nat. Methods 20, 1203–1212 (2023).
Camargo, A. P. et al. Identification of mobile genetic elements with geNomad. Nat. Biotechnol. 42, 1303–1312 (2024).
Jain, C., Rodriguez-R, L. M., Phillippy, A. M., Konstantinidis, K. T. & Aluru, S. High throughput ANI analysis of 90K prokaryotic genomes reveals clear species boundaries. Nat. Commun. 9, 5114 (2018).
Blanco-Míguez, A. et al. Extension of the Segatella copri complex to 13 species with distinct large extrachromosomal elements and associations with host conditions. Cell Host Microbe 31, 1804–1819 (2023).
Chang, H.-W. et al. Prevotella copri and microbiota members mediate the beneficial effects of a therapeutic food for malnutrition. Nat. Microbiol. 9, 922–937 (2024).
Maguire, F. et al. Metagenome-assembled genome binning methods with short reads disproportionately fail for plasmids and genomic Islands. Microb. Genom. 6, mgen000436 (2020).
Abramova, A., Karkman, A. & Bengtsson-Palme, J. Metagenomic assemblies tend to break around antibiotic resistance genes. BMC Genomics 25, 959 (2024).
Xing, L. et al. ErmF and ereD Are Responsible for Erythromycin Resistance in Riemerella anatipestifer. PLoS ONE 10, e0131078 (2015).
Huttenhower, C. et al. Structure, function and diversity of the healthy human microbiome. Nature 486, 207–214 (2012).
He, X. et al. Cultivation of a human-associated TM7 phylotype reveals a reduced genome and epibiotic parasitic lifestyle. Proc. Natl Acad. Sci. USA 112, 244–249 (2015).
Kazantseva, E., Donmez, A., Frolova, M., Pop, M. & Kolmogorov, M. Strainy: phasing and assembly of strain haplotypes from long-read metagenome sequencing. Nat. Methods 21, 2034–2043 (2024).
Shaw, J., Gounot, J.-S., Chen, H., Nagarajan, N. & Yu, Y. W. Floria: fast and accurate strain haplotyping in metagenomes. Bioinformatics 40, i30–i38 (2024).
Jochheim, A. et al. Strain-resolved de-novo metagenomic assembly of viral genomes and microbial 16S rRNAs. Microbiome 12, 187 (2024).
Grigoriev, A. Analyzing genomes with cumulative skew diagrams. Nucleic Acids Res. 26, 2286–2290 (1998).
Schmidt, S., Toivonen, S., Medvedev, P. & Tomescu, A. I. Applying the safe-and-complete framework to practical genome assembly. Leibniz Int. Proc. Inform. 312, 8 (2024).
Dabbaghie, F., Ebler, J. & Marschall, T. BubbleGun: enumerating bubbles and superbubbles in genome graphs. Bioinformatics 38, 4217–4219 (2022).
Lancia, G., Bafna, V., Istrail, S., Lippert, R. & Schwartz, R. SNPs problems, complexity, and algorithms. In Proc. 9th Annual European Symposium on Algorithms (ed. auf der Heide, F. M.) 182–193 (Springer, 2001).
Chaung, K. et al. SPLASH: A statistical, reference-free genomic algorithm unifies biological discovery. Cell 186, 5440–5456 (2023).
Ondov, B. D. et al. Mash: Fast genome and metagenome distance estimation using MinHash. Genome Biol. 17, 132 (2016).
Liu, X. et al. Nanopore strand-specific mismatch enables de novo detection of bacterial DNA modifications. Genome Res. 34, 2025–2038 (2024).
Delahaye, C. & Nicolas, J. Sequencing DNA with nanopores: troubles and biases. PLoS ONE 16, e0257521 (2021).
Roberts, M., Hayes, W., Hunt, B. R., Mount, S. M. & Yorke, J. A. Reducing storage requirements for biological sequence comparison. Bioinformatics 20, 3363–3369 (2004).
Shaw, J. & Yu, Y. W. Theory of local k-mer selection with applications to long-read alignment. Bioinformatics 38, 4659–4669 (2022).
Belbasi, M., Blanca, A., Harris, R. S., Koslicki, D. & Medvedev, P. The minimizer Jaccard estimator is biased and inconsistent. Bioinformatics 38, i169–i176 (2022).
Frith, M. C., Shaw, J. & Spouge, J. L. How to optimally sample a sequence for rapid analysis. Bioinformatics 39, btad057 (2023).
Shaw, J. & Yu, Y. W. Proving sequence aligners can guarantee accuracy in almost O(m log n) time through an average-case analysis of the seed-chain-extend heuristic. Genome Res. 33, 1175–1187 (2023).
Chen, J.-Q. et al. Variation in the ratio of nucleotide substitution and indel rates across genomes in mammals and bacteria. Mol. Biol. Evol.26, 1523–1531 (2009).
Spouge, J. L., Das, P., Chen, Y. & Frith, M. The statistics of parametrized syncmers in a simple mutation process without spurious matches. J. Comput. Biol. 31, 1195–1210 (2024).
Hoeffding, W. & Robbins, H. The central limit theorem for dependent random variables. Duke Math. J. 15, 773–780 (1948).
Stanojević, D., Lin, D., de Sessions, P. F. & Šikić, M. Telomere-to-telomere phased genome assembly using error-corrected Simplex nanopore reads. Preprint at bioRxiv https://doi.org/10.1101/2024.05.18.594796 (2024).
Nurk, S. et al. The complete sequence of a human genome. Science 376, 44–53 (2022).
Tan, K.-T., Slevin, M. K., Meyerson, M. & Li, H. Identifying and correcting repeat-calling errors in nanopore sequencing of telomeres. Genome Biol. 23, 180 (2022).
Jain, C. Coverage-preserving sparsification of overlap graphs for long-read assembly. Bioinformatics 39, btad124 (2023).
Li, H. & Durbin, R. Genome assembly in the telomere-to-telomere era. Nat. Rev. Genet. 25, 658–670 (2024).
Blanca, A., Harris, R. S., Koslicki, D. & Medvedev, P. The statistics of k-mers from a sequence undergoing a simple mutation process without spurious matches. J. Comput. Biol. 29, 155–168 (2022).
Liu, D. & Steinegger, M. Block Aligner: an adaptive SIMD-accelerated aligner for sequences and position-specific scoring matrices. Bioinformatics 39, btad487 (2023).
Vaser, R., Sović, I., Nagarajan, N. & Šikić, M. Fast and accurate de novo genome assembly from long uncorrected reads. Genome Res. 27, 737–746 (2017).
Lee, C., Grasso, C. & Sharlow, M. F. Multiple sequence alignment using partial order graphs. Bioinformatics 18, 452–464 (2002).
Shaw, J. & Yu, Y. W. Fast and robust metagenomic sequence comparison through sparse chaining with skani. Nat. Methods 20, 1661–1665 (2023).
Kruchten, N., Seier, A. & Parmer, C. An interactive, open-source, and browser-based graphing library for Python. Zenodo https://doi.org/10.5281/zenodo.14503524 (2025).
Köster, J. & Rahmann, S. Snakemake—a scalable bioinformatics workflow engine. Bioinformatics 28, 2520–2522 (2012).
O’Leary, N. A. et al. Exploring and retrieving sequence and metadata for species across the tree of life with NCBI Datasets. Sci. Data 11, 732 (2024).
Wick, R. R. Badread: simulation of error-prone long reads. J. Open Source Softw. 4, 1316 (2019).
Gurevich, A., Saveliev, V., Vyahhi, N. & Tesler, G. QUAST: quality assessment tool for genome assemblies. Bioinformatics 29, 1072–1075 (2013).
Mikheenko, A., Saveliev, V. & Gurevich, A. MetaQUAST: evaluation of metagenome assemblies. Bioinformatics 32, 1088–1090 (2016).
Pan, S., Zhao, X.-M. & Coelho, L. P. SemiBin2: self-supervised contrastive learning leads to better MAGs for short- and long-read sequencing. Bioinformatics 39, i21–i29 (2023).
Eren, A. M. et al. Anvi’o: an advanced analysis and visualization platform for ‘omics data. PeerJ 3, e1319 (2015).
Rahman Hera, M., Pierce-Ward, N. T. & Koslicki, D. Deriving confidence intervals for mutation rates across a wide range of evolutionary distances using FracMinHash. Genome Res. 33, 1061–1068 (2023).
Chaumeil, P.-A., Mussig, A. J., Hugenholtz, P. & Parks, D. H. GTDB-Tk: a toolkit to classify genomes with the Genome Taxonomy Database. Bioinformatics 36, 1925–1927 (2020).
Price, M. N., Dehal, P. S. & Arkin, A. P. FastTree 2 – approximately maximum-likelihood trees for large alignments. PLoS ONE 5, e9490 (2010).
Alcock, B. P. et al. CARD 2023: expanded curation, support for machine learning, and resistome prediction at the Comprehensive Antibiotic Resistance Database. Nucleic Acids Res. 51, D690–D699 (2023).
Schwengers, O. et al. Bakta: rapid and standardized annotation of bacterial genomes via alignment-free sequence identification. Microb. Genom. 7, 000685 (2021).
Bouras, G., Grigson, S. R., Papudeshi, B., Mallawaarachchi, V. & Roach, M. J. Dnaapler: a tool to reorient circular microbial genomes. J. Open Source Softw. 9, 5968 (2024).
Gilchrist, C. L. M. & Chooi, Y.-H. Clinker & clustermap.js: automatic generation of gene cluster comparison figures. Bioinformatics 37, 2473–2475 (2021).
Marçais, G. et al. MUMmer4: a fast and versatile genome alignment system. PLoS Comput. Biol. 14, e1005944 (2018).
Letunic, I. & Bork, P. Interactive Tree Of Life (iTOL) v5: an online tool for phylogenetic tree display and annotation. Nucleic Acids Res. 49, W293–W296 (2022).
Kirkegaard, R. & Albertsen, M. MicroBench: nanopore data for microbial genomic benchmarking. Zenodo https://doi.org/10.5281/zenodo.18492140 (2026).
Acknowledgements
This work is supported by US National Institute of Health grant no. R01HG010040 to H.L. J.S. is supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) Postdoctoral Fellowship award (no. PDF-587396). We thank H. Cheng, X. Feng and members of the Li lab for helpful discussions. We thank M. Albertsen and R. Kirkegaard for benchmarking dataset support. We thank M. Sereika and T. Nielsen for providing valuable software feedback.
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J.S. and H.L. conceived the project. J.S. implemented the method and devised the algorithms with guidance from H.L. J.S. conducted the benchmarking analyses. J.S. and M.G.M. performed the horizontal gene transfer analyses. J.S. wrote the manuscript with contributions from H.L. and M.G.M. All authors read and approved the final version of the manuscript.
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QUAST metrics for synthetic long-read metagenome experiments.
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Benchmarking metrics and datasets for the concatenated mock metagenome experiments.
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Dataset description and timing results for the real long-read metagenomes.
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Shaw, J., Marin, M.G. & Li, H. High-resolution metagenome assembly for modern long reads with myloasm. Nat Biotechnol (2026). https://doi.org/10.1038/s41587-026-03053-z
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DOI: https://doi.org/10.1038/s41587-026-03053-z


