Nanohalarchaeota

Nanohalarchaeota is a phylum of diminutive archaea with small genomes and limited metabolic capabilities, belonging to kingdom Nanobdellati. They are ubiquitous in hypersaline habitats, which they share with the extremely halophilic haloarchaea.

Nanohaloarchaea were first identified from metagenomic data as a class of uncultivated halophilic archaea composed of six clades and were subsequently placed in the phylum Nanohalarchaeota within the DPANN clade (kingdom Nanobdellati). However, the phylogenetic position of nanohaloarchaea is still highly debated, being alternatively proposed as the sister-lineage of haloarchaea or a member of the Nanobdellati kingdom.

The lineage has since been identified in data from a range of hypersaline environments including: Australian thalassohaline lake, Spanish saltern, Russian soda brine, Californian saltern, Chilean halite, and Ethiopian Dallol hydrothermal system. Like most other members of DPANN, they are only known to live with a host (specifically a similarly halophilic archaeon) in symbiosis. The exact nature of this interaction with the host vary among species, from mutualism to parasitic predation.