Biology of Marine Fungi
Although marine fungi are extremely potent producers of secondary metabolites and bioactive substances, research on marine fungi has suffered neglect. A literature survey covering more than 23,000 bioactive microbial products, i.e. antifungal, antibacterial, antiviral, cytotoxic and immunosuppressive agents, shows that the producing organisms are mainly from the fungal kingdom. Hence, fungi represent one of the most promising sources of bioactive compounds. Therefore, fungi derived from marine sources are considered to represent a huge reservoir of secondary metabolites. However, the number of strains available from marine sources is limited and the knowledge of marine fungi in general is scarce. In order to describe and understand the biology of marine fungi with respect to their secondary metabolite production and their ecological role, we focussed on marine fungi. New isolation campaigns, molecular work and the large strain collection of marine isolates are the basis for these activities. An example is given by the studies of fungi associated to sponges. Marine sponges harbour a high diversity of fungi. Fungi isolated from Tethya aurantium were isolated and identified both by morphological criteria and phylogenetic analysis based on internal transcribed spacer (ITS) regions and were evaluated with regard to their secondary metabolite profiles (Wiese et al., 2011). More than 200 isolates were obtained, part of these (81 isolates) were characterised. They belong to 21 different genera. Some of these were quite common, such as Acremonium, Aspergillus, Fusarium, Penicillium, Phoma, and Trichoderma, while others have rarely been reported from sponges. These include representatives of Botryosphaeria, Epicoccum, Parasphaeosphaeria, and Tritirachium. Members affiliated to the genera Bartalinia and Volutella as well as a presumably new Phoma species were not previously isolated from sponges.
On the basis of their classification, strains from the sponge were selected for analysis of their natural products. In addition to a variety of known substances, several new natural products were found. The new cyclodepsipeptides scopularide A and B were produced by a Scopulariopsis brevicaulis and these peptides and their activities have been patented because of their antiproliferative activities against several tumor cell lines. We described e.g. the new antibiotic cillifuranone produced by a Penicillium chrysogenum and helicusin E, isolated from a Bartalinia strain (Jansen et al., 2013)).
The applied aspects are under investigation e.g. in the frame of the EU-FP7 research project “MARINE FUNGI” (project number 265926), which focusses on the development of anti-cancer drugs from marine fungi. “MARINE FUNGI” covers two approaches to gain effective producer strains, which will be led to the stage of in vivo proof of concept building the basis for clinical trials. Despite marine fungi are a potent group of secondary metabolite producers, they are not well characterized and underutilized in terms of biotechnological application. We demonstrate the sustainable exploitation of marine natural resources providing appropriate culture conditions for the group of marine fungi, thus enabling efficient production of marine natural products in the laboratory (see www.marinefungi.eu).
We are planning to intensify approaches with the aim to get more insights into the biological role of bioactive compounds and their fungal producers living in association with macroorganisms. Geographic distribution of marine fungi, genetic specificities of marine isolates compared to terrestric ones and interaction studies, are the topics that were recently started in our group.
Head of the Research Unit:
Prof. Dr. Johannes F. Imhoff
GEOMAR | Helmholtz Centre for Ocean Research Kiel
Düsternbrooker Weg 20
Phone: ++49-431 600-4450
Fax: ++49-431 600-4482
Personal Assistant / Office Management:
Phone: ++49-431 600-4481
Fax: ++49-431 600-4482