Oyster mushrooms shrink, paralyze nematode heads in the wild

We add soybean hull pellets to the growing medium for most of our Oyster mushrooms and we didn’t know exactly why. We recently realized they replace something other than dead wood and organisms in the wild. 

Soybean hulls, the outer skin of soybeans, are the hearty source of protein and nitrogen in the growth mix. The two nutrients develop the mushroom's essential components and structures. Soybean hulls are dense enough in nutrients to support the aggressive growing behaviour of the Oyster mushrooms, which can go from spores to fruitbodies in as little as two weeks. 

Oyster mushrooms do not see many soybean hulls flying around in the wild – the hulls are a by-product of oil extraction from soybean seeds. 

Instead, they prey on live nematodes.

Some of the most common Oyster mushrooms, the Snow Oysters (Pleurotus ostreatus) and Italian Oysters (Pleurotus pulmonarius), immobilize nematodes with toxins, according to experts in Brazil. That way, the nematodes have nowhere to go as the mushroom’s hyphae arrive, penetrate, and digest them. 

One toxin, linoleic acid, shrinks the nematode’s head and displaces its esophagus as part of paralyzing the microscopic insect, according to a report from Toho University in Japan. 

Nematodes became the unlucky choices for head shrinking and fungi feeding because they provide nitrogen.

Nitrogen is often luxurious in dead hardwood trees where wild Oyster mushrooms grow. Many fungi will not survive because there is not enough nitrogen around. However, dead wood is a popular host for microscopic insects and bacteria that do contain nitrogen.

The extra nitrogen supports the saprophytic mushrooms to grow strong and continue to build a network of mycelia throughout the soil. 

But wait – live nematodes sound like a cheat food for the Oyster mushrooms since saprophytes are supposed to grow and feed on dead organic matter.

That’s because Oyster mushrooms behave as facultative parasites whenever they find the opportunity to add some bonus nutrients, according to senior scientist Bogdan Jaroszewicz at the University of Warsaw. This means they do not rely on taking nutrients from live organisms to survive but can resort to parasitic activity to support the life cycle.

The mushrooms don’t need to be parasitic indoors at JCB Gourmet Mushrooms. 

While we don’t have nematodes in our growing medium, mushroom cultivation requires mimicking a wild habitat. Our growing medium contains hardwood pellets, the dead wood that would host fungi outdoors. The polypropylene bags act as the bark, retaining moisture and keeping the growing medium in its place. 

Soy hull pellets save the hassle of shrinking heads and paralyzing live insects so our Oyster mushrooms can skip straight to the eating and growing. That means more fresh mushrooms are available for you to enjoy; just take a look at our shop!