Cyanate, a by‐product of urea decomposition, is a potential nitrogen (N) source in marine environments, but to date it has received scant attention. Cyanobacteria presumably acquire this compound via a substrate‐specific ABC‐type transporter ( cynABD ), and they convert it to ammonium and carbon dioxide by cyanase ( cynS ) activity. Participation of cyanate utilization genes in N‐stress responses in cyanobacteria has been impl...