MetaPalette: ak-mer Painting Approach for Metagenomic Taxonomic Profiling and Quantification of Novel Strain Variation.
Metagenomic profiling is challenging in part because of the highly uneven sampling of the tree of life by genome sequencing projects and the limitations imposed by performing phylogenetic inference at fixed taxonomic ranks. We present the algorithm MetaPalette, which uses longk-mer sizes (k= 30, 50) to fit ak-mer "palette" of a given sample to thek-mer palette of reference organisms. By modeling thek-mer palettes of unknown organisms, the method also gives an indication of the presence, abundance, and evolutionary relatedness of novel organisms present in the sample. The method returns a traditional, fixed-rank taxonomic profile which is shown on independently simulated data to be one of the most accurate to date. Tree figures are also returned that quantify the relatedness of novel organisms to reference sequences, and the accuracy of such figures is demonstrated on simulated spike-ins and a metagenomic soil sample. The software implementing MetaPalette is available at: https://github.com/dkoslicki/MetaPalette. Pretrained databases are included forArchaea,Bacteria,Eukaryota, and viruses.IMPORTANCETaxonomic profiling is a challenging first step when analyzing a metagenomic sample. This work presents a method that facilitates fine-scale characterization of the presence, abundance, and evolutionary relatedness of organisms present in a given sample but absent from the training database. We calculate a "k-mer palette" which summarizes the information from all reads, not just those in conserved genes or containing taxon-specific markers. The compositions of palettes are easy to model, allowing rapid inference of community composition. In addition to providing strain-level information where applicable, our approach provides taxonomic profiles that are more accurate than those of competing methods.Author Video: An author video summary of this article is available.
Mathematics Department, Oregon State University, Corvallis, Oregon, USA.
David
D
Koslicki
Institute of Life Sciences, University of Swansea, Singleton Park, Swansea, United Kingdom.
Daniel
D
Falush
metagenomics; quantitative methods; taxonomic profiling