Advancing source tracking: systematic review and source-specific genome database curation of fecally shed prokaryotes

Abstract

Approaches for shotgun metagenomic sequencing are being adapted to many environmental monitoring tasks but remain poorly suited for source attribution within fecal source tracking (FST) studies due to a lack of knowledge regarding the source specificity of fecally shed microbial populations. To address this gap, we performed a systematic literature review and curated a large collection of genomes (n=26,018) representing fecally shed prokaryotic species across broad and narrow source categories commonly implicated in FST studies of recreational waters (i.e., cats, dogs, cows, seagulls, chickens, pigs, birds, ruminants, human feces, and wastewater). These data include genome sequences recovered from metagenomic and isolation-based studies which we examined extensively with comparative genomic approaches to characterize trends across source categories and produce a finalized genome database for each source category which is available online (n=12,730). We find that across these sources, the total number of genomes recovered varies substantially: from none in seagulls to 9,085 in pigs.According to available data, on average 81% of the genomes representing species-level populations occur only within a single source. Using fecal slurries to test the performance of each source database, we report read capture rates that vary with fecal source alpha diversity and database size. Lastly, while extensive work has been performed on the rumen system of cows and other ruminants, we note the scarcity of genomic characterization of prokaryotes in the feces of these animals. We expect this resource to be useful to FST-related objectives, One Health research, and sanitation efforts globally.Table of Contents Graphical AbstractSynopsisWe curate nine prokaryotic genomic databases for fecal source-tracking, summarize their source-specificity, and show their usefulness by bioinformatically testing mock impaired surface water samples.