Nitrate and ammonia as nitrogen sources for deep subsurface microorganisms. Nitrogen cycling groundwater bacteria

The nitrogen cycling bacterial community at 100 m depth in crystalline bedrock groundwater was investigated using nitrate and ammonium as substrates in a stable isotope probing study. The bacterial community was enriched with 15N ammonium or nitrate for 28 days after which the enriched community and the nitrogen assimilating communities were compared using 454 amplicon sequencing of the 16S rRNA genes