Analysis of nitrous oxide reductase diversity from wastewater: a SINTAX database

This study explores the genetic landscape of nitrous oxide (N2O) reduction
in wastewater treatment plants (WWTPs) by profiling 1083 high-quality
metagenome-assembled genomes (HQ MAGs) derived from 23 Danish full-scale
WWTPs. The analysis focuses on the distribution and diversity of nitrous
oxide reductase (nosZ) genes, key players in N2O reduction, and their
connection to other nitrogen metabolism pathways. A custom pipeline for
clade-specific nosZ gene identification outperformed existing methods,
revealing the presence of 503 nosZ sequences in 489 MAGs. Notably, 48.7%
of the MAGs harboured nosZ genes, with clade II dominating (92.3%).
Taxonomic profiling reveals the distribution of nosZ clade I and clade
II-containing MAGs, emphasizing the dominance of Bacteroidota and
Pseudomonadota. Notably, Chloroflexota exhibits unexpected affiliations
with nosZ clade I. The taxonomic diversity of non-denitrifying
N2O-reducers is also explored, highlighting the presence of these
organisms in Bacteroidota, Chloroflexota, and other phyla.