New paper in Nature

Michael Wagner and his team discovered cyanate as a sufficient single substrate for nitrifiers. The ammonia-oxidzing thaumarchaeote Nitrososphaera gargensis is the first known microbe that can grow on cyanate  as only energy source by using a cyanase to convert this compound into ammonium and CO₂. In addition, all genome-sequenced nitrite-oxidizing bacteria possess cyanases and can grow on cyanate by teaming up with cyanase-negative ammonia-oxidizers via a novel reciprocal feeding mechanism.