The role of lichenized algae in the production of Cladonia verticillaris depsidones, revealed by using alginate-immobilized cells

Abstract

The mycobiont of the lichen Cladonia verticillaris produces two depsidones, protocetraric and fumarprotocetraric acids, in the nature. This last compound is produced from the former depsidone. To study the role of the algal partner in the production of these depsidones in the lichen thallus, fungal and algal partners were separated and immobilized in calcium alginate. The fungal immobilizates, as lichenized or isolated mycobiont, produced both depsidones, preferently fumarporotocetraric acid from acetate as a precursor. However, when algal immobilizates were co-incubated on acetate with the fungal ones, protocetraric acid was over-produced during the first 11 days of incubation to be later converted into fumarprotocetraric acid. We hypothesized about the algal production of a diffusible metabolite that inhibits the transformation of a depsidone into the other one.