The reduced genomes of Parcubacteria (OD1) contain signatures of a symbiotic lifestyle

摘要: Candidate phylum OD1 bacteria (also referred to as Parcubacteria) have been identified in a broad range of anoxic environments through community survey analysis. Although none these species isolated the laboratory, several genome sequences reconstructed from metagenomic sequence data and single-cell sequencing. The organisms small (generally <1 Mb) genomes with severely reduced metabolic capabilities. We 8 partial near-complete oxic groundwater samples, compared them against existing genomic data. conserved core gene set comprises 202 genes, or ~28% complement. "Housekeeping" genes for biosynthesis peptidoglycan Type IV pilus production are conserved. Gene sets cofactors, amino acids, nucleotides, fatty acids absent entirely greatly reduced. only aspects energy metabolism non-oxidative branch pentose-phosphate shunt central glycolysis. These also lack some activities almost all other known bacterial genomes, including signal recognition particle, pseudouridine synthase A, FAD synthase. Pan-genome analysis indicates genotypic diversity perhaps highly fluid complement, indicating historical adaptation wide growth high degree specialization. were examined signatures suggesting either free-living, streamlined lifestyle, symbiotic lifestyle. biosynthetic capabilities DNA repair, along presence potential attachment adhesion proteins suggest that Parcubacteria ectosymbionts parasites organisms. potentially mediate cell-cell contact suggests partner/prey across phylum.