A global map of microbial genes

Patterns in the distribution of microbial genes across biomes has implications for both human, animal and planetary health. Bork and colleagues report the construction of a microbial gene catalogue using over 13,000 metagenomic datasets spanning 14 habitats. Their analysis suggests that most genes are specific to a single habitat, although mobile genes and antibiotic resistance genes are widespread. Clustering of the sequences into protein families revealed that a small fraction of families contain the majority of the genes. By analysing sequence variation, the data suggests that most genetic variability observed within each protein family is neutral or nearly neutral.