|Coolen, M. J. L., B. Abbas, J. van Bleijswijk, E. C. Hopmans, M. M. M. Kuypers, S. G. Wakeham and J. S. Sinninghe Damsté, Putative ammonia-oxidizing Crenarchaeota in suboxic waters of the Black Sea: a basin-wide ecological study using 16S ribosomal and functional genes and membrane lipids., Environmental Microbiology, 9(4), 1001-1016 (2007)|
Within the upper 400 m at western, central, and eastern stations in the world’s largest stratified basin, the Black Sea, we studied the qualitative and quantitative distribution of putative nitrifying Archaea based on their genetic markers (16S rDNA, amoA encoding for the alfa-subunit of archaeal ammonia monooxygenase), and crenarchaeol, the specific glycerol diphytanyl glycerol tetraether (GDGT) of pelagic Crenarchaeota within the Group I.1a. Marine Crenarchaeota were the most abundant Archaea (up to 98% of the total archaeal 16S rDNA copies) in the suboxic layers with oxygen levels as low as 1 µM including layers where previously anammox bacteria were described (Kuypers et al., 2003). Different marine crenarchaeotal phylotypes (both 16S rDNA and amoA) were found at the upper part of the suboxic zone as compared to the base of the suboxic zone and the upper 15-30 m of the anoxic waters with prevailing sulfide concentrations of up to 30 µM. Crenarchaeol concentrations were higher in the sulfidic chemocline as compared to the suboxic zone. These results indicate an abundance of putative nitrifying Archaea at very low oxygen levels within the Black Sea and might form an important source of nitrite for the anammox reaction. Full Article is available here.