Bioproduction of lichen phenolics by immobilized lichen cells with emphasis on the role of epiphytic bacteria

Abstract

SUMMARY. Since 1966, immobilization of lichen cells or enzymes in inert, hydrophilic matrices by adsorption or entrapment is the usual method to improve the production of lichen metabolites without biomass destruction. Alginate and polyacrylamide are used for cell entrapment, whereas bioskin, clays or polyhydroxyurethane have been largely preferred as matrices for immobilization by adsorp tion. Entrapped or adsorbed cells can be used to induce a particular metabolic transformation, i.e., lecanoric acid into orsellinic acid, or, alternatively, to produce lichen phenolics from acetate as a pri mary precursor. The overall production of some of these phenolics, such as evernic and usnic acids, atranorin, parietin and fumarprotocetraric acid, is reviewed and analyzed the possible role in the process of phenolic production and accumulation of epiphytic bacteria contaminating lichen immo bilisates.