When human meets the jellyfish that met fungi

Humans got used to avoiding jellyfishes for obvious reasons, however, these invertebrates can be perfect hosts for microorganisms, providing a space for ecological interactions that have a potential to become models for biotechnological applications.

Yue et al (2015) collected jellyfishes Nemopilema nomurai during the jellyfish bloom in China aiming to find a biotechnological application for abundant organisms that caused problems in local waters. They sampled for the fungal communities on the umbrella, tentacles, and gonad and managed to isolate seven fungal colonies. Two isolates were sampled from tentacles, other five strains were from subumbrella (inside part of the umbrella). No fungi were isolated from exumbrella (top part of the umbrella) and gonad. 

They then extracted the DNA and amplified fungal ITS fragment with PCR. DNA sequences were BLAST searched and phylogenetic tree built. Two fungal phyla were found: Ascomycota and Basidiomycota with Ascomycota being dominant.
Interestingly, species that has not been commonly found in the marine environment was isolated - three isolates out of seven were represented by Tilletiopsis spp. The diversity of fungal community found was much less compared to those isolated from benthic cnidarians in previous studies and authors suggested that it might be due to the important defensive role of metabolites against predators in invertebrates that do not possess toxins.
To see, what maximizes the metabolite production, authors tried different culturing media and co-cultivation. They obtained 13 extracts and showed the variation in metabolite composition between pure strains and co-cultures with HPLC analysis.

All of the extracts displayed different levels of antibacterial activity; three of them (Cladosporium sp, Tilletiopsis sp.) exhibited a significant antibacterial activity to the bacterial pathogens Staphylococcus aureus and Salmonella entrica. Fungal species Cladosporium sp. has previously been shown to exhibit microbial properties.

Tilletiopsis sp., was able to inhibit A. versicolor, showing the evidence of competitive interaction between fungal species. A. versicolor extracts solely and extracts from co-culture with Tilletiopsis sp. showed antifungal properties suggesting the potential for the further implication as agricultural fungicides. These results indicate the defensive metabolite production by suppressed A. versicolor.

This is not the first work showing jellyfish derived fungi producing metabolites with antimicrobial properties: cytochalasin derivatives were isolated from the Phoma sp. fungus obtained from the same species jellyfish. (Jung and et al., 2012)
This paper was focused on the biotechnological meaning of findings, but there is also has an ecological side. Not much work has been done on the jellyfish microbiome, and the fact that both in this work and in the work done by Jung and et al., (2012), fungi were isolated from the inner jellyfishes tissues, makes the reader consider a possibility for the symbiotic interaction between the jellyfish and fungi. Therefore it would be interesting to look for the common fungal microbiome within the jellyfish in future studies.

Considering the fact, that antibacterial properties were found for the fungal extracts and that no fungi were isolated from bacteria-rich parts of the jellyfish, this system might be an example of competition between bacteria and fungi. Authors did not look on the bacterial community present on the jellyfish and it would be interesting to apply the same co-culture and different media methods with fungi and bacteria specific to the host. The study by Mille-Lindblom et. al., (2006) shows the presence of competition for the substrate between marine fungi and bacteria that involves the production of metabolites.  Therefore, bacteria-fungal interactions can be an interesting biotechnological model to study.

This paper provides an evidence for fungal potential in the biotechnological application, however, is lacking the genomic approach. It would be interesting to 1) identify the compounds extracted 2) see which genes are responsible for the production, possibly with gene knock out and 3) look at the gene expression profiles under different conditions.

Personally, I think that this work presents another example of an interesting two (three?) side interaction that is not yet well-understood. It also shows natural systems of interactions (fungi-bacteria, fungi-fungi) that can have a potential use in biotechnology and should be studied more.

Paper reviewed:

Yue, Y., Yu, H., Li, R., Xing, R., Liu, S. and Li, P. (2015). Exploring the Antibacterial and Antifungal Potential of Jellyfish-Associated Marine Fungi by Cultivation-Dependent Approaches. PLOS ONE, 10(12)

Further reading:

Mille-Lindblom, C., Fischer, H. and J. Tranvik, L. (2006). Antagonism between bacteria and fungi: substrate competition and a possible trade-off between fungal growth and tolerance towards bacteria. Oikos, 113(2), pp.233-242.

Jung, J. and et al., e. (2012). ChemInform Abstract: Cytotoxic Cytochalasins from the Endozoic Fungus Phoma sp. of the Giant Jellyfish Nemopilema nomurai. ChemInform, 43(38)