Removing Host-derived DNA Sequences from Microbial Metagenomes via Mapping to Reference Genomes

DNA sequencing has become a common tool in environmental microbial ecology, facilitating characterization of microbial populations as well as complex microbial communities by circumventing culture bottlenecks. However, certain samples especially from host-associated environments (rhizosphere, human tissue) or complex communities (soils) can contain a high degree of DNA sequences derived from hosts (plants, human) or other organisms of non-interest (arthropods, unicellular eukaryotes). This chapter presents a simple in silico method to remove contaminating sequences in metagenomes based on aligning sequences to reference genomes of the target organism.