Metagenomic ventures into outer sequence space

Dutilh, Bas E

In the short term, ignoring the unknowns can facilitate the interpretation of a metagenome. Because a taxonomic or functional description cannot be provided, the classical questions in metagenomics are left unanswered for the unknown fraction of the metagenome, and concentrating on the annotated sequences leads to a more straightforward answer. However, unexpected or novel sequences are quickly overlooked, even if they represent highly abundant or widespread organisms. Thus, in the long term, stockpiling the unknown sequencing reads in badly accessible bulk sequence repositories can severely slow down research, the discovery of novel species, and the charting of biological sequence space.