The Atlantis II Deep Brine Pool (ABP), located at >2 km depth in the Red Sea rift valley, is a hydrothermally active brine pool characterized by elevated temperature (~68 °C), high salinity (~250 psu), anoxic conditions, and high metal concentrations. These characteristics position ABP as an ideal modern analog for the harsh environments of early Earth, where life first emerged and evolved under similar physicochemical constraints. In this study, we profiled virus communities and estimated taxon-specific microbial cell lysis from four layers of the ABP (overlying seawater, brine-seawater interface, mid-brine, and bottom brine). We discovered 6759 species-level DNA viral populations (vOTUs) from >15 viral families. The vast majority of vOTUs are specific to the ABP, and share little to no similarity to other viral metagenomic datasets and reference virus databases, indicating the unique viral landscape in ABP. The ABP viruses primarily infect prokaryotes, with the predicted hosts derived from six archaeal and 16 bacterial phyla. Virus communities detected in the ABP are as diverse as those found at the sea surface and appear to be active. By sequencing extracellular 16S rRNA in the ABP stratified layers, cell lysis was detected in taxa from nine out of 22 prokaryotic phyla including Proteobacteria, Crenarchaeota, and Thermoplasmatota, indicating widespread viral lysis activity that contributes to microbial community structuring and the cycling of carbon and nutrients in the ABP. In addition, viruses in the ABP possess a variety of auxiliary metabolic genes (AMGs), which may aid in the promotion of host metabolism and adaptation in response to harsh environmental conditions. Together, this research reveals an active, diverse, and functionally potent viral community that plays a central role in microbial dynamics, adaptation and biogeochemical cycling in one of Earth's most extreme marine environments, offering new insights into how viruses may have influenced early microbial evolution and supported life’s persistence under primordial conditions.

Viruses Diversity