Phylogeny-Aware Analysis of Metagenome Community Ecology Based on Matched Reference Genomes while Bypassing Taxonomy

Area of Science:

• Microbiology
• Bioinformatics
• Computational Biology

Background:

• Shotgun metagenomics offers powerful insights into microbial communities but faces computational challenges and limited feature resolution with current taxonomic classification-based analyses.
• Existing methods often struggle to fully leverage the potential of shotgun metagenomic data for detailed community analysis and phylogenetic inference.
• 16S rRNA gene amplicon studies commonly use phylogenetic methods, which are less frequently applied to shotgun metagenomics.

Purpose of the Study:

• To introduce the operational genomic unit (OGU) method, a novel metagenome analysis strategy for enhanced microbial community assessment.
• To enable maximal resolution of community composition and integrate phylogenetic analyses into shotgun metagenomics.
• To provide a bioinformatics tool (Woltka) for the practical implementation of the OGU method.

Main Methods:

• The OGU method utilizes sequence alignment hits to individual reference genomes as the fundamental unit for analysis, bypassing taxonomic classification.
• It organizes genomic features into a phylogenomic hierarchy, supporting advanced analytical protocols like UniFrac and phylofactorization.
• The method was validated using two real-world case studies, including the Human Microbiome Project and the FINRISK 2002 cohort.

Main Results:

• The OGU method demonstrated superior performance over taxonomic unit-based analyses and 16S rRNA gene amplicon sequence variants in identifying biologically meaningful patterns.
• It showed stronger correlations with host factors like body environment and sex in the Human Microbiome Project data.
• The method achieved more accurate prediction of human age from gut microbiomes in the Finnish cohort, even at low sequencing depths.

Conclusions:

• The OGU method provides maximal resolution of microbial community composition and enables the use of phylogeny-aware tools in shotgun metagenomics.
• It offers significant advantages over current methods for uncovering biologically relevant insights and predicting host traits.
• The OGU method, implemented in Woltka, is proposed as an effective and adoptable practice for future metagenomic studies.