Ammonia oxidation, denitrification and dissimilatory nitrate reduction to ammonium in two US Great Basin hot springs with abundant ammonia-oxidizing archaea

作者：Dodsworth Jeremy A; Hungate Bruce A; Hedlund Brian P^*

来源：Environmental Microbiology, 2011, 13(8): 2371-2386.

DOI：10.1111/j.1462-2920.2011.02508.x

Many thermophiles catalyse free energy-yielding redox reactions involving nitrogenous compounds; however, little is known about these processes in natural thermal environments. Rates of ammonia oxidation, denitrification and dissimilatory nitrate reduction to ammonium (DNRA) were measured in source water and sediments of two similar to 80 degrees C springs in the US Great Basin. Ammonia oxidation and denitrification occurred mainly in sediments. Ammonia oxidation rates measured using (15)N-NO(3)(-) pool dilution ranged from 5.5 +/- 0.8 to 8.6 +/- 0.9 nmol N g(-1) h(-1) and were unaffected or only mildly stimulated by amendment with NH(4)Cl. Denitrification rates measured using acetylene block ranged from 15.8 +/- 0.7 to 51 +/- 12 nmol N g(-1) h(-1) and were stimulated by amendment with NO(3)(-) and complex organic compounds. The DNRA rate in one spring sediment measured using an (15)N-NO(3)(-) tracer was 315 +/- 48 nmol N g(-1) h(-1). Both springs harboured distinct planktonic and sediment microbial communities. Close relatives of the autotrophic, ammonia-oxidizing archaeon 'Candidatus Nitrosocaldus yellowstonii' represented the most abundant OTU in both spring sediments by 16S rRNA gene pyrotag analysis. Quantitative PCR (qPCR) indicated that 'Ca. N. yellowstonii' amoA and 16S rRNA genes were present at 3.5-3.9 10(8) and 6.4-9.0 10(8) copies g(-1) sediment. Potential denitrifiers included members of the Aquificales and Thermales. Thermus spp. comprised < 1% of 16S rRNA gene pyrotags in both sediments and qPCR for T.

• 出版日期2011-8