The dark matter of our microbiomeThough rapid progress has been made in understanding the microbiome’s impact on human health, a fundamental issue remains largely unsolved; and it is preventing the field from making the transition from developing therapeutics based on serendipity to inventing medicine at scale using engineering principles. This issue, at its heart, is the murky understanding of the so-called “dark matter” in the human microbiome. Collectively, the dark matter refers to th