FIG. 1.

Physical maps of environmental gene contigs involved in denitrification processes. Shown are the nosZ clusters (purple), the nirS clusters (yellow), genes from the CRP/FNR family involved in the expression control of the denitrification process (brown), the nirK clusters (green), and other genes not directly involved in the denitrification process (orange), which are described in Tables S1 to S9 in the supplemental material.