DPANN

DPANN is a proposed superphylum within the domain Archaea that groups several ultra-small, often symbiotic or parasitic archaeal lineages identified through metagenomic and single-cell genomic analyses. The name DPANN comes from the initials of traditionally recognized core members: Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, and Nanohaloarchaeota. Additional lineages, such as Woesearchaeota, have been associated with the DPANN assemblage in later studies, though the exact composition varies with different analyses.

Members of DPANN are notable for extremely small cell sizes and frequently reduced genomes. Many lack complete biosynthetic pathways for amino acids, nucleotides, or lipids and are thought to rely on interactions with other microorganisms, including symbiotic or parasitic relationships, for growth and survival. Metabolic capabilities vary among lineages, with some capable of limited fermentation while others appear to depend heavily on hosts or neighboring microbes for essential nutrients.

DPANN lineages have been detected in a wide range of environments, including marine and terrestrial subsurfaces, hydrothermal vents, hypersaline lakes, soils, and groundwater. Most members remain uncultured, with knowledge derived mainly from environmental genomes and, in a few cases, from studies of specific host associations, such as Nanoarchaeum equitans with its host Ignicoccus hospitalis.

Phylogenetically, the monophyly of DPANN is debated. Some analyses place DPANN as a coherent, early-branching archaeal clade, while others suggest it comprises multiple, distantly related lineages or represents rapid evolutionary radiation. The unresolved relationships have implications for understanding archaeal evolution and the origins of symbiotic lifestyles. DPANN remains a focus of ongoing genomic exploration to clarify its diversity and biology.