Candidatus Nitrosopumilus halotolerans single-cell genome sequencing. Nitrosopumilus sp. RSA3

This project aimed at illuminating the genomic signatures of adaptation among microorganisms residing in the brine-seawater transition layer of several brines lakes occuring at the bottom of the Red Sea. Most interesting among these microorganisms are the ammonia-oxidizing Archaea (AOAs), which are important in the global nitrogen cycle, and predominate the deep-sea realm of the global ocean. Because salinity is predicted as a major constrain on the activities of ammonia-oxidizers based on energetics for osmotolerance, we hypothesized that such metabolic groups should become diminished with increasing salt concentrations. Our study was therefore designed to unravel the mechanisms of halo-tolerance in a novel and abundant thaumarcheon found in the brine-seawater interface of Atlantis II Deep.