Cultivation of some mushrooms species originating from Tunisia and exploration of their valuable metabolites

Mushrooms present interests for consumption as food, as traditional medicine or in bioremediation, due to their nutritional, antioxidant, antimicrobial, therapeutic and enzymatic values. The valorisation of indigenous species of mushrooms requires well characterized collections. Although macrofungi are widespread in Tunisian forests, their diversity and ecology remain generally underexplored which hindered their exploitation. In particular, the in vitro cultivation of the mycelial form could have many advantages: (a) it offers faster growth rates which may have industrial and biotechnological benefits, and (b) will allow better resource management (longer conservation of active forms) and genetic manipulation. To achieve these objectives, more than 55 regular expeditions to Tunisian forests were organized. Several hundreds of indigenous species of mushrooms were collected and macroscopically and microscopically identified. Mycelial cultivation of newly collected specimens allowed obtaining 57 isolates of basidiomycetes. Specific molecular analysis by sequencing ITS regions showed that the isolates belong to the following genera: Agaricus (9), Ganoderma (5), Amanita (5), Boletus (4), Lactarius (3), Lepista (3), Tapinella (3), Pleurotus (3), Macrolepiota (3), Gymnopilus (2), Lentinus (2), Polyporus (2), Tricholomopsis (2), Rhizopogon (2), Hygrophorus (2), Armillaria (2), Pisolithus (1), Paxillus (1), Hericium (1), Russula (1), and Coprinus (1). On the other hand the cultivated species were screened for their enzyme production on specific solid and liquid media namely laccase, cellulase and amylase.Preliminary results showed that the majority of species produce high levels of laccase activity and the number of extracellular laccase isoenzymes seems to be species dependent. Potentially interesting produced enzymes will be purified and characterized. In addition the possibility of submerged cultivation and biologically active polysaccharides production by some medicinal species was also examined. Preliminary results showed that several species are producing antiviral polysaccharides. Further analyses are required to characterize the active biomolecules and to investigate the action mode. Additional tests on immunomodulatory, hypoglycemia, cholesterol lowering, antioxidant, antiinflammatory, antimicrobial and antitumor properties are planned. This work on mushrooms originating from Tunisia may contribute to diversify the range of mushrooms for domestic market and for obtaining innovative products.