Could fungi help to clean polluted water?

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That was the question explored by Paige, one of the students whose research has brought a new areas of interest for New Forest Water Watch.

Paige’s project looked at mycoremediation – the use of fungi to help remove or transform pollutants. She chose the oyster mushroom, Pleurotus ostreatus, and investigated what happened when its mycelium was placed in water collected from the Beaulieu River.

Over six days, Paige followed a series of samples and used multi-compound water test strips to look for changes in the substances they contained. She found that readings for a number of the substances measured by the strips decreased during the experiment. The size of the changes varied between samples, and one sample in particular showed some of the largest reductions and also produced the largest fungal fruiting body.

Those observations are interesting – but they raise just as many questions as they answer.

For example, was it the fungal mycelium itself that caused the changes? Could some substances have been taken up or adsorbed by the fungal material or the substrate in which it was growing? And, importantly, if a substance is no longer detected in the water, where has it gone?

There is another intriguing observation in Paige’s experiment. The hessian substrate used with the fungus coloured the water quite strongly. That means that the experimental system itself was changing the water, and raises the question of how much of the observed change was due specifically to the living fungus.

This is exactly what makes exploratory research valuable. Paige’s project did not set out to provide a definitive answer to whether fungi can clean polluted water. Instead, it produced some intriguing observations and, perhaps more importantly, a set of questions that could be investigated with a more controlled experiment.

Maybe a next step could be to separate the different parts of the system, comparing water with living fungal mycelium against water with the substrate alone, for example, and to use very precise methods of measuring particular substances. That would help establish not simply whether something changes, but what changes, by how much, and what might be responsible.

For New Forest Water Watch, this is an exciting. Our monitoring programme generates a large amount of real-world information about water quality across the Forest and it’s great that student projects could take some of those observations and ask quite different scientific questions of their own.

Paige has already done the most important part of any investigation: she asked an interesting question, designed an experiment, collected observations and, in doing so, uncovered some new questions.

We’re looking forward to seeing where those questions lead next

Photos: Pleurotus ostreatus fruiting bodies, and mycelium growing through straw. Photo: Rob Hille, Wikimedia Commons