Nitrous oxide reductase gene cluster of Wolinella succinogens (top) and Sulfurospirillum spp. (bottom). Color scheme was maintained from reference [18]. Green ORFs encode for nitrous oxide reductase, yellow ORFs encode a conserved trans-membrane protein, blue ORFs encode for nos accessory proteins, purple ORFs encode for 4Fe-4S proteins, red ORFs encode for c-type cytochromes, and white ORFs (labeled 1–5) represent additional predicted genes not found in the W. succinogens nos cluster. Putative function of additional ORFs: 1. Hypothetical protein (Locus tag: OA34_06690), 2. ABC transporter permease (OA34_10365), 3. ABC transporter ATP-binding protein (OA34_10360), 4. Hypothetical protein (OA34_10355), 5. Hypothetical protein (OA34_06670). Note: ORFs not drawn to scale, the length of the predicted protein (in amino acid residues) encoded by each gene is provided.