The Utilization of Urea by the Lichen Cladonia sandstedei.

The production of both ribitol (which is the translocatable form of reduced carbon) and mannitol (which is the main accumulation form of carbon) by thallus samples of Cladonia sandstedei increases when exogenous urea is supplied to the lichen. In addition, the synthesis of atranorin and its precursor, methyl β-orcinol carboxylate, is also enhanced by urea. A hypothetical action of ammonia released from this nitrogen source on these metabolic processes is suggested.