Table 1: Primer sets for the PCR amplification of archaeal genes that encode key enzymes of nitrogen metabolism.

Process in N cycleKey enzymeTarget genePrimer namePrimer sequenceReference

Ammonia monooxygenase
(E.C. 1.14.99.39.)
amoA arc-Amo-f
arc-Amo-r
5′-STAATGGTCTGGCTTAGACG-3′ 
5′-GCGGCCATCCATCTGTATGT-3′ 
[18]
Ferredoxin nitrite reductase
(E.C. 1.7.7.1.)
nirA arc-NirA-f
arc-NirA-r
5′-AAYMTSCCNCGGAAGTKSAA-3′ 
5′-AGAACTCCBTRCCSGTRCAS-3′ 
This study
Ammonifying nitrite reductase
(E.C. 1.7.1.4.)
nirB arc-NirB-f
arc-NirB-r
5′-ATGCTGAGCCATTAYATAGC-3′ 
5′-CCGTTGTACTCGGCRCAGTC-3′ 
This study
Nitrous oxide reductase
(E.C. 1.7.2.4.)
nosZ arc-Nos-f
arc-Nos-r
5′-TGGGGHGACTMYCAYCAYCC-3′ 
5′-AKGTGKCCRRSGTTGTAGTK-3′ 
This study
Nitrogenase reductase
(E.C. 1.18.6.1.)
nifH arc-Nif-f
arc-Nif-r
5′-TAYGGAAARGGNGGNATYGG-3′ 
5′-CCNCCRCAGACRACRTCNCC-3′ 
This study
Dissimilatory nitrate reductase
(E.C.1.7.99.4.)
napA, narG arc-Nred-f
arc-Nred-r
5′-CGACTGGTAYKCVGAYCTHC-3′ 
5′-GTCRGYGTKRWACCAGTSGK-3′
This study