Identification of the mycobiota associated to the marine echinoderm Holothuria poli and investigation of cytotoxic and pro‐osteogenic potential of isolated strains.

Fungal strains were isolated from the animal’s body‐wall, intestine and faeces. The species identification was based on DNA barcoding and morphophysiological observations. Forty‐seven species were identified, all are Ascomycota and mainly belonging to Aspergillus and Penicillium genera. Sixteen strains were grown on three media for chemical extraction. Cytotoxic activity was tested on a hepatic cancer cell line (HepG2), the cells viability was evaluated after treatment using a resazurin based assay (AlamarBlue). Pro‐osteogenic activity was tested on human Mesenchymal stem cell, differentiation was measured as the alkaline phosphatase production through reaction with p‐nitrophenylphosphate or as the cells ability to mineralize calcium using a colorimetric kit (StanBio). Cytotoxic activity was recorded for four fungal species while five of 48 extracts highlighted bioactivity towards human mesenchymal stem cells.

The presence of relevant animal‐associated mycobiota was observed in H. poli and selected strains showed cytotoxic potential and pro‐osteogenic activity.

Our work represents the first report of a Mediterranean Sea cucumber mycobiota and highlights the isolates potential to synthetize compounds of pharmaceutical interest for regenerative medicine.