Of
these, the abundance of nirS gene, encoding a component of the
nitrite reductase enzyme (NO
2
!
NO), has been linked to rates of
total denitrification, and the ratio of nirS and nosZ (nitrous oxide
reductase; NO
!
N2O) linked to the
final N2O:N2 molar ratios
(Morales et al., 2010; Regan et al., 2011). Nitrification is another key
step coupling nitrogen mineralization and denitrification