Cyanate - a low abundant but actively cycled nitrogen compound in soil

Cyanate (NCO-) can serve as a nitrogen and/or carbon source for different microorganisms and even additionally as an energy source for autotrophic ammonia oxidizers. Despite the widely distributed genetic potential for direct cyanate utilization among bacteria, archaea and fungi, the availability and environmental significance of cyanate is largely unknown, especially in terrestrial ecosystems. We found relatively low concentrations of soil cyanate, but its turnover was rapid. Contrary to our expectations, cyanate consumption was clearly dominated by biotic processes, and, notably, cyanate was produced in-situ at rates similar to that of cyanate formation from urea fertilizer, which is believed to be one of the major sources of cyanate in the environment. Our study provides evidence that cyanate is actively turned over in soils and represents a small but continuous nitrogen/energy source for soil microbes, potentially contributing to a selective advantage of microorganisms capable of direct cyanate utilization.