2020/07/01 by Jeffrey S. McLean, Batbileg Bor, Kristopher A. Kerns +7 · 1 citation
Biochemistry, Genetics and Molecular Biology · Environmental Science · #Genomics and Phylogenetic Studies #Gut microbiota and health #Bacteriophages and microbial interactions
paper · pdf · doi:10.1016/j.celrep.2020.107939
openalex publication_date 2020/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
The first cultivated representative of the enigmatic phylum Saccharibacteria (formerly TM7) was isolated from humans and revealed an ultra-small cell size (200-300 nm), a reduced genome with limited biosynthetic capabilities, and a unique parasitic lifestyle. TM7x was the only cultivated member of the candidate phyla radiation (CPR), estimated to encompass 26% of the domain Bacteria. Here we report on divergent genomes from major lineages across the Saccharibacteria phylum in humans and mammals, as well as from ancient dental calculus. These lineages are present at high prevalence within hosts. Direct imaging reveals that all groups are ultra-small in size, likely feeding off commensal bacteria. Analyses suggest that multiple acquisition events in the past led to the current wide diversity, with convergent evolution of key functions allowing Saccharibacteria from the environment to adapt to mammals. Ultra-small, parasitic CPR bacteria represent a relatively unexplored paradigm of prokaryotic interactions within mammalian microbiomes.