An improved method for the separation of lichen symbionts

A novel method for the isolation of lichen photobionts by density gradient centrifugation has been assessed using the lichen Evernia prunastri as an experimental model. An initial sucrose-KI gradient was prepared in which algae and small hyphal fragments formed an interphase in a sucrose-KI gradient. Then, 10 mM phosphate buffer is added and the preparation centrifuged a second time. This partitioned the algal cells towards the buffer while the bulk of the fungal hyphae were retained in the sucrose solution. This method allowed the purification of algal cells with no contamination from the fungal partner.