Characterization of culturable truffle-inhabiting fungi isolated from Tuber melanosporum, T. aestivum and T. borchii ascomata

Truffles in the genus Tuber host and feed a wide community of organisms including insects, bacteria, and fungi. Among microorganisms, truffle-inhabiting fungi (TIF) have been poorly investigated and only a limited number of yeast and filamentous species have been identified. In this work we isolated and barcoded culturable TIF from 16 ascomata of T. melanosporum, T. aestivum and T. borchii of different provenances. Eighteen strains were identified a species level, four at genus level and one at order level. Penicillium was the most represented genus with five species and the only TIF genus isolated from T. melanosporum ascomata. Six TIF had colonies with a yeast morphology, including two species of Candida. Five species (Leohumicola sp., Knufia tsunedae, Hypocreales sp., Sagenomella cf. verticillata, Kondoa sp.) had rare ITS sequences compared to those deposited in GenBank. Except Peniophora cinerea, all TIF identified in this work have never been reported in Tuber ascomata until now. In-depth investigations on TIF and their host specificity are needed to evaluate the effects of these fungi on the truffle life cycle and the quality of ascomata.