Astin C production by the novel fungus Cyanodermella asteris in planktonic conditions in comparison to biofilm state

Secondary metabolites produced by plants or their symbionts have already shown interesting biological activities: anticancer, anti-inflammatory, antibacterial, antifungal effects, etc. Astin C is a peptide (secondary metabolite) isolated from the medicinal plant Aster tataricus and showing anticancer activity. Recent investigations have shown that astin is a non-ribosomal peptide synthesized by the fungus Cyanodermella asteris, a novel endosymbiont of the plant. This discovery opened the possibility to producing astin C on a large scale with a high productivity through bioreactor technologies. In this work, a comparison between astin C production by C. asteris in planktonic and immobilized cultures was investigated. The fungus was first studied in terms of its ability to attach firmly to solid supports in stainless steel. It was demonstrated that the fungal hyphae were able to grow specifically on that support and to produce astin C with a higher productivity than in planktonic cultures. The influence of the types of inoculum (mycelium or spores) and the nature of the solid support, differing in their hydrophobicity, were analysed. It was found that the fungal attachment and the astin C productivity were significantly affected by these two factors.