PRODUCTION OF RIBITOL BY ALGINATE-IMMOBILIZED CELLS OF THE LICHEN CLADONIA-VERTICILLARIS

Cells of the lichen Cladonia verticillaris have been immobilized in calcium alginate and incubated for 15 days in light on different concentrations of sodium bicarbonate in order to produce lichen polyols. Sugars and polyols secreted to the medium were extracted and analyzed by HPLC. Production and secretion of both ribitol and glucose were very high by entrapped cells incubated on 10 mM sodium bicarbonate but the replacement of calcium by sodium in the alginate matrix produced the disorganization of the immobilized system in a period no longer than 5 days. However, incubation of the entrapped cells on 1 mM sodium bicarbonate preserved the structure of the innert matrix altough only ribitol was produced and secreted to the medium. Entrapment in sodium alginate maintained cell vitality although chloroplast disorganization of the phycobiont became evident. Moreover, contact between myco- and phycobiont has also been altered during immobilization since algal ribitol was not converted into mannitol by the fungal partner.