Archaea with a sweet tooth: isolation of novel sugar-degrading thermoacidophiles

While numerous deep-branching lineages of Archaea have been found over the last two decades, most of them still remain enigmatic and uncultivated. In their article, Prokofeva et al. report the isolation of two species from a thermoacidophilic lineage previously reported as "Candidatus Marsarchaeota" and propose a renaming to Tardisphaeria (M. I. Prokofeva, A. I. Karaseva, A. S. Tulenkov, A. A. Klyukina, et al., mSystems 10:e00710-25, 2025, https://doi.org/10.1128/msystems.00710-25). Cultivation coupled with genome analysis revealed a strong enrichment and co-occurrence of polysaccharide and sugar metabolisms in these archaea relative to other thermoacidophiles. These polyextreme archaea were also found to make up large abundances (up to 40% relative abundance) in acidic hot springs, indicating they are important for carbon cycling in these environments. These organisms may also host biotechnologically relevant genes for using polysaccharides that are stable at high temperatures and low pH. Overall, these new isolates improve our understanding of archaeal diversity and metabolism and open the door for more studies on these previously inaccessible organisms.