Patescibacteria is the bacterial superphylum also known as the Candidate Phyla Radiation (CPR) 1. It appears in this corpus in two roles. First, the Bacillota_B project uses it as the literature contrast case for genome streamlining in subsurface bacteria 1. Second, its amplicon abundance is enriched in shallow sediment 2.
Aliases: Patescibacteria; CPR; Candidate Phyla Radiation superphylum 1.
Genome streamlining as a contrast case
The Bacillota_B subsurface project sets its main result against Tian et al. (2020)‘s “small is mighty” streamlining finding 1. The report describes its own result as running in the opposite direction 1. Within cultivable bacillota-b, deep-clay specialization correlates with gene-content expansion rather than reduction 1. These organisms are anaerobic Firmicutes that grow free-living rather than as episymbionts 1.
The report adds its own caveat: Tian’s claim was specific to the Patescibacteria/CPR superphylum, which Tian’s finding characterises by genomes of ≤1 Mbp and an episymbiotic lifestyle 1. Bacillota_B occupies a different subsurface niche, so the report treats Patescibacteria only as a literature contrast for a lineage-specific pattern and does not present a direct contradiction. The project’s own genome comparison covers Bacillota_B, not Patescibacteria 1.
The report also connects the expansion pattern to Beaver & Neufeld (2024)‘s “self-sufficiency” hypothesis 1. It further connects the pattern to Becraft et al. (2021)‘s Ca. Desulforudis audaxviator, whose genome GB_GCA_020725505.1 is in the project’s anchor cohort 1. According to the report, Becraft showed that this genome is self-sufficient, with full N-fixation, amino-acid biosynthesis and C-fixation, and has not been streamlined 1. The cross-project discussion is in subsurface-bacillota-specialization and biosynthetic-self-sufficiency-and-cultivation 1.
Depth distribution in ENIGMA SSO sediments
The ENIGMA SSO ASV ecology analysis lists Patescibacteria among the shallow-enriched phyla, in the zone the report labels vadose and oxic 2. Its depth correlation is ρ = −0.70 2. The other shallow-enriched phyla are Chloroflexi (ρ = −0.73), Myxococcota (−0.54) and Spirochaetota (−0.53) 2. The oxic label is an inference, not a measurement: the report states that all of its environmental inferences come from community composition alone and still await geochemical confirmation 2. This is an amplicon-level association, so it does not speak to genome size or lifestyle. For more, see subsurface-hydrogeological-zonation 2.