During the 1960s, small quantities of radioactive materials were co-disposed with chemical waste at the Little Forest Legacy Site (LFLS, Sydney, Australia). The microbial function and population dynamics during a rainfall event using shotgun metagenomics has been previously investigated. This revealed a broad abundance of candidate and potentially undescribed taxa in this iron-rich, radionuclide-contaminated environment.Here, applying genome-based metagenomic methods, we recovered 37 refined archaeal bins (≥50% completeness, ≤10% redundancy) from 10 different major lineages. They were, for the most part, included in 4 proposed lineages within the DPANN supergroup (LFWA-I to IV) and Methanoperedenaceae .The new Methanoperedens spp. bins, together with previously published data, suggests a potentially widespread ability to use nitrate (or nitrite) and metal ions as electron acceptors during the anaerobic oxidation of methane by Methanoperedens spp.While most of the new DPANN lineages show reduced genomes with limited central metabolism typical of other DPANN, the candidate species from the proposed LFWA-III lineage show some unusual features not often present in DPANN genomes, i.e. a more comprehensive central metabolism and anabolic capabilities. While there is still some uncertainty about the capabilities of LFW-121_3 and closely related archaea for the biosynthesis of nucleotides de novo and amino acids, it is to date the most promising candidate to be a bona fide free-living DPANN archaeon.

Genomic insights into the Archaea inhabiting an Australian radioactive legacy site