Cartoon comparison of human genomes (above) and E. coli (below) as a representative bacterium. In humans, genetic variation is dominated by relatively sparse single nucleotide polymorphisms (SNPs), nucleotide diversity π = 0.001, and less than 1% of a typical genome lies in a structural variant (SV) . Human genomes are therefore relatively compressible. In stark contrast, genes make up around 88% of an E. coli genome , yet two E. coli genomes may only share around 60% of their genes , and conserved genes have much higher nucleotide diversity (0.02) . Thus, bacterial genomes present different compression and indexing challenges to human genomes. 1. The 1000 Genomes Project Consortium. A global reference for human genetic variation. Nature 526, 68-74, doi:10.1038/nature15393 (2015). 2. Blattner, F. R. et al. The complete genome sequence of Escherichia coli K-12. Science 277, 1453-1462 (1997). 3. Touchon, Marie, et al. "Organised genome dynamics in the Escherichia coli species results in highly diverse adaptive paths." PLoS genetics 5.1 (2009): e1000344. 4. Kaas, Rolf S., et al. "Estimating variation within the genes and inferring the phylogeny of 186 sequenced diverse Escherichia coli genomes." BMC genomics 13.1 (2012).