Polysaccharides present in cultivated Teloschistes flavicans symbiosis: Comparison with those of the thallus

The chemical structures of polysaccharides present in aposymbiotically cultured myco- and photobionts of the lichen Teloschistes flavicans were determined, in order to compare them with those previously found in the intact thallus. The mycobiont was cultured on a solid Lilly and Barnett medium and the resulting colonies were freeze dried, defatted, and their polysaccharides were extracted successively with 2%, 10% and 30% aq. KOH, each at 100 °C. The extracts were neutralized (HOAc) and fractionated, giving rise to three homogeneous fractions, PFSK2 from 2% KOH, which contained a (1 → 4),(1 → 6)-linked α-glucan (1:1 ratio, pullulan), fraction PK10 from 10% KOH extraction, which was a linear (1 → 3)-linked linear β-glucan (laminaran), and fraction PK30 from 30% KOH extraction, being a branched (1 → 3),(1 → 6)-linked β-glucan. The photobiont (Trebouxia sp. de Puymaly) was cultured in liquid nutrient medium, and after purification, a linear (1 → 5)-linked β-galactofuranan was characterized. The galactofuranan and the laminaran were not present in the symbiotic thallus, in contrast to the glucans, showing that the mycobiont alone produces them without participation of the photobiont.