Targeted metagenomics using probe capture detect a larger diversity of nitrogen and methane cycling genes in complex microbial communities than traditional metagenomics.

Microorganisms are key players in the global cycling of nitrogen and carbon, controlling their availability and fluxes, including the emissions of the powerful greenhouse gases nitrous oxide and methane. Standard sequencing methods often reveal only a limited fraction of their diversity, because of their low relative abundance, the insufficient sequencing depth of traditional metagenomes of complex communities, and limitations in coverage of DNA amplification-based assays. Here, we developed and tested a targeted metagenomics approach based on probe capture and hybridization to simultaneously characterize the diversity of multiple key metabolic genes involved in inorganic nitrogen and methane cycling. We designed comprehensive probe libraries for each of the 14 target marker genes comprising 264 111 unique probes. In validation experiments with mock communities, targeted metagenomics yielded gene profiles similar to the original communities. Only GC content had a small effect on probe efficiency, as low GC targets were less efficiently detected than those with high GC, within the mock communities. Furthermore, the relative abundances of the marker genes obtained using targeted or traditional shotgun metagenomics were significantly correlated. In addition, using archaeal