Decomposing Hydraulic Oil with Oyster Mushrooms — Part 1

Nothing says “party” quite like a box of greasy shop rags.

A friend generously gifted me a large cardboard box filled with rags soaked in hydraulic oil from a tractor-hose leak. Rather than discard them, I decided to feed them to mushrooms.

Mycoremediation, briefly

Mycoremediation is the use of fungi to remediate contaminated landscapes. Mushrooms can break down environmental and industrial chemicals and pathogens. A few notable examples:

• Oyster mushrooms excel at decomposing hydrocarbons (oil, gas, diesel)
• Wine Caps can digest E. coli
• Shiitake handles textile dyes

I’ve worked with this kind of thing before. Previously I had a barrel of mixed vehicle fluids — diesel, waste vegetable oil, engine coolant — and I inoculated ten jars of Oyster mushroom mycelium at various contamination levels. Over three months, each jar learned to digest the black sludge, and the contamination gradually disappeared entirely.

Bench test

For this round, I ran initial tests with cardboard and blue cotton rags, each placed in jars with Blue Oyster spawn. Filter disks and drilled lids allowed air exchange.

Results after 10 days:

1. Hydraulic-oil-soaked cardboard showed strong Pleurotus ostreatus mycelium growth.
2. Oil-soaked cotton rag exhibited almost no mycelium growth.
3. Yellow fluid (exudates / metabolites) appeared in the cardboard jar, indicating enzymatic decomposition of the hydraulic oil.

Testing and further investigation

Mycelium growth doesn’t, on its own, confirm complete decomposition of the harmful components. To check that, I’m running a bioassay — germinating beans exposed to various concentrations of the contaminated material — to test toxicity and efficacy.

Two hypotheses for why the cotton rag didn’t take off:

1. Oil concentration may be too high, inhibiting the organism.
2. Mycelium may prefer cardboard over cotton — though this is the less-likely explanation, since I’ve previously grown mushrooms on jeans without trouble.

What’s next

Part 2 will cover the bioassay results, introduce a new fungal species, and advance the experimental phase. This is open citizen-science work — if you want to be involved, or you have a contamination problem on your land or in your operation that you think mycoremediation could help with, get in touch.