Tissue cultures of Usnea rubescens and Ramalina yasudae and production of usnic acid in their cultures.

Usnic acid acts on gram-positive bacteria1} and is used as a skin germicide, but is not industrially produced.It is widely spread in Usneaceae lichens,2) but these lichens are not abundant in nature and their culture is very difficult because their spores are not always obtained in natural habitats, they are almost always sterile, and natural lichen thalli are