Ratio of singleton vs. non-singleton bacteria in human microbiome

The human genome comprises about 20,000 genes, but that pales by comparison to the millions of genes in the human microbiome, according to a Harvard study.  “To determine this quantity, the researchers conducted a meta-analysis of metagenomes from the human mouth and gut among 3,655 samples from 13 unique studies.” They wrote, “We found staggering genetic heterogeneity in the dataset, identifying a total of 45,666,334 non-redundant genes (23,961,508 oral and 22,254,436 gut) at the 95% identity level.”  But that’s just a rough estimate.  As one researcher commented: “There may be more genes in the collective human microbiome than stars in the observable universe, and at least half of these genes appear to be unique to each individual,. . . .”  MORE

Image Credit:   Harvard Microbiome Diversity Study