Bioactivity and Secondary Metabolome Profiling of Marine Fungi Associated with the Seagrass Zostera marina

Fungi have played a historical role in discovery and development of life-saving drugs, such as antibiotics and anticancer drugs. Despite being an important portion of marine microbiome, chemical composition and the biotechnological potential of fungi from marine resources have so far remained underexplored. The eelgrass Zostera marina forms wide marine landscapes in the Northern Hemisphere and play a significant role in the welfare of marine ecosystems. In continuation of our work on seagrasses and marine fungi [1,2], we have investigated fungi associated with Z. marina and its surrounding sediment. Fourteen fungal strains, with a high proportion of Penicillium sp. (10 sp.) were obtained. The organic extracts of liquid cultures in five different culture media (with/without shaking) were tested for bioactivity. All extracts showed strong (up to 100% at 100 µg/mL concentration) anti-quorum sensing activity against Allivibrio fischerii and antimicrobial activity against marine pathogens Pseudoalteromonas elyakovii and Vibrio anguillarum. HPLC-DAD-MS-based secondary metabolome (SM) analyses of the extracts indicated the high influence of culture conditions on the SM profiles. Chemical diversity was high and dereplication was successful. For example, among 66 compounds detected in all Penicillium sp. belonged to the classes of alkaloids, polyketides, and terpenoids and 45 were successfully assigned to known compounds. Analysis of SM relatedness in culture conditions by Hierarchical Cluster Analysis revealed generally low similarity. Specifically, one Penicillium strain (P-85) formed a very distinct group in terms of its SM. Further Principal Component Analysis biplots revealed the strong effect of medium selection on SM profiles of P-85. This strain is now being cultivated in large-scale for in-depth metabolomics and bioactivity-guided isolation studies.

[1] Orhan I, Sener B, Brun R, Perozzo R, Tasdemir D. Phytomedicine, 2006, 13, 388 – 393.

[2] Silber J, Kramer A, Labes A, Tasdemir D. Mar Drugs 2016; 14, doi: 10.3390/md14070137.