Around 7,500 mushroom-forming fungi are safely stored in liquid nitrogen at the Wageningen Campus. José Kuenen is in charge of maintaining this extensive collection. She is the first point of contact for every researcher or grower needing material from the collection. According to insiders, she is better placed than anyone to spot how a mushroom will develop.
José Kuenen has been a research assistant since 1977. When the Mushroom Experimental Station moved from Horst to Wageningen in 2006, she came with it. “In the early days, we carried out a lot of experiments for growers looking for new mushroom varieties. That’s also how the famous U1 variety came into being: the round, firm button mushroom that has been cultivated for many years. ‘We'll never get a better one than this,’ I said at the time.”
‘You have to have a feel for it’
In the 1980s, the quality of cultivated mushrooms was still assessed entirely by human eye. Technology has taken over some of the screening work over the years. But according to Kuenen, you really need to see with your own eyes what a mushroom species looks like before you decide to place it on the market. She has a razor-sharp eye: “You have to have a feel for it: during the growth cycle I can see very quickly whether there are abnormalities forming. You also need to have a feel for preparing the spawn that the mushrooms grow on. You have to be able to tell exactly when to use the spawn. If you cook it for too long, so much starch is released that it makes it unworkable. That’s not something you can measure with equipment.”
When researchers need cultures from the collection, it is Kuenen they contact. "If they need a particular fungus, I take a piece of it out of the nitrogen and we grow it. As soon as it is ready, I pass it on to the researcher. We have been using this system with nitrogen since 2006. When I first started, all the cultures were still stored on tubes in a refrigerated room. We had to inoculate all the material every year back then. Fortunately, we don’t have to do that any more.”
Growers who encounter abnormalities during cultivation – which happens quite often – also come to Kuenen. “When a species with abnormalities is brought in, we dive into the collection and look for a similar species. Then we use DNA to trace exactly where the abnormality arose and what caused it: is it due to the cultivation climate or is it a hereditary matter? That saves growers a huge amount of time: because the collection is always to hand, you can get down to work on the solution fast."
Kuenen loves her work: “A mushroom is such a special organism. When I collect the spores from a single mushroom, each one can develop into a completely different fungus. Some grow slowly, some grow cloud-like and others develop in strands. I still find it fascinating, even after all these years."