INTRODUCTION
Microbial denitrification is a key pathway in global nitrogen cycling
and has been studied extensively for its role in fixed nitrogen loss and
as a source of potent greenhouse gases (Zumft, 1997; Decleyre et
al. , 2016). Diverse bacteria are capable of denitrification, often
facultatively using nitrate or nitrite as an alternative electron
acceptor in oxygen-limited zones. Several diverse microorganisms have
the genomic capacity to perform complete denitrification (Fig. 1),
reducing nitrate to dinitrogen gas (Philippot, 2002; Canfield, Glazer
and Falkowski, 2010).