Though they aren't as charismatic as a red and white fly agaric mushroom, marine fungi perform important and unique ecosystem functions. Scientists have found marine fungi in diverse environments from coral reefs to marine sediments at the bottom of the ocean.
Historically, marine fungi have been understudied—most scientists, much less the general public, don't know much about marine fungi. They aren't visible to the naked eye like mushrooms we see on land (mushrooms are the fruiting bodies, or reproductive structures of some species of fungi). Moreover, studying marine fungi previously required time-intensive culturing methods.
Now, more species of marine fungi have been discovered along with the wave of microbial research conducted with next generation DNA sequencing techniques. However, current sampling methods can be biased against collection of marine fungal species and sequencing methods can only tell us so much.
A new piece in Current Biology Magazine, summarizes the state of marine fungi research and highlights future research directions. The scientists write:
If fungi have a superpower, it is their ability to degrade and metabolize recalcitrant polymers. Fungi, as a matter of fact, were the first organisms to degrade lignin: leading to a period of rapid diversification and reallocation of global carbon.
Recalcitrant polymers are basically compounds that are very difficult to break down by most organisms. Wood is the best example of this. Fungi break down the tough lignin that houses easily accessible carbon. After this, other organisms like bacteria decompose the simpler carbon compounds.
These are other superpowers of marine fungi:
Marine fungi have unique adaptations to salinity and intense pressures found in the deep ocean.
High salinity stresses the osmotic balance of cells, so any species that live in the ocean or other saline environments must adapt or it will perish. Terrestrial fungi rely on pressurizing their cells against rigid cell walls when they divide, which is not possible in saltwater.
To overcome this challenge, marine fungi have more salt efflux pumps in their cell membranes and they create compounds called osmolytes that allow them to function in saltwater. While marine fungi can survive in seawalter, it seems that they do not necessarily prefer it, since there is a cost to maintaining these adaptations.
Intense hydrostatic pressures found in the deep ocean cause the machinery of cells to become less stable and for cell membranes to become less fluid, both of which challenge basic cellular functions. Marine fungi have adapted by using proteins (the machinery of cells) that work at high pressure.
There is potential for marine fungi to help combat our oil spills and microplastics crisis.
After the Deepwater Horizon oil spill, fungi increased dramatically in marine sediments around the site. Fungi have been found in all sorts of extreme environments and some species can degrade plastics and hydrocarbons. This has obvious potential applications to microplastics polluting our oceans and the Great Pacific Garbage Patch as well as oil spills.
We shouldn't continue business-as-usual hoping that fungi will save us on this front (fungi already help us grow crops and some species have anti-inflammatory properties that help with human health). We should reduce plastic pollution and prevent future oil spills. In the meantime, these potential applications of fungi could help us clean the mess we've already made. More research is required on this front.
Moving forward, marine fungi should be studied to help us understand carbon cycling budgets. Marine fungi research can also be applied to natural product development, including blue biotechnology. Natural product development is a burgeoning field aimed at discovering compounds in the environment that could be used to treat human disease via antimicrobial and anticancer compounds.
