Gobnjak, an urban mushroom farm under Rožnik Hill in Ljubljana, is the place of work for bionics engineer Rok Zalar and microbiologist Primož Turnšek. This is where they grow different types of mushrooms from the mycelium to full-grown mushroom, which requires a lot of handiwork. They share their knowledge and experience in mushroom growing at workshops, where they are assisted by mycologist Katarina Grabnar Apostolides. The ace up Gobnjak’s sleeve is mushroom grow kits. With their work, the Gobnjak team raises awareness about mushrooms and their uses in contemporary culture.
Together with amateur mycologist Katarina Grabnar Apostolides they organise mushroom foraging, mushroom cultivation, and mushroom watching workshops. They occasionally collaborate with the Slovenian Forestry Institute, Biotechnical Faculty of the University of Ljubljana, and Zavod Kersnikova institute.
Rok Zalar first caught the mushroom bug in 2015 as an amateur brewer. He was interested in the circular principle in food production, because spent brewers’ grain makes a good substrate ingredient. Having graduated in bionics in engineering, he turned to fungiculture and in 2018 set up the first urban farm without land – Gobnjak, which he established with Bojana Rudovič Žvanut. In Gobnjak, mushrooms grow in a closed, humid basement grow-room, where the temperature is regulated at 15–20 °C. A year ago, the Gobnjak team had a makeover: Bojana said goodbye and microbiologist Primož Turnšek joined in her place. He had experience with mushrooms, as he had been making wood plugs for mushroom growing and experimenting with fungi as an innovative packaging material.
Gobnjak operates in the premises of a former bar in Ljubljana’s district of Rožna Dolina. This is where they grow mycelium from live cultures of various mushrooms, prepare grow kits, and produce and process fresh mushrooms. Growing mushrooms involves a lot of handiwork, and to bear fruit live organisms require a sterile environment, especially in the early stages of mycelium growth. As a microbiologist, Primož is in charge of the first steps of the process, and Rok takes the helm in the subsequent stages. They have seen a growing interest in mushroom growing recently, which they attribute to increased awareness of their healing properties and culinary uses, and they try to promote interest in mushrooms through their business endeavours. For several years, they have been organising monthly workshops on mushroom growing and foraging. As they are a seasonal venture that depends on the mushroom growing season, most of their educational programmes take place in spring and autumn, when online sales of accessories and products increase as well.
Primož and Rok’s ambition is to grow more species of saprophytic fungi, and they’re also full of big ideas for expanding their offer. Voracious readers of scientific articles, they are constantly looking for opportunities to exchange knowledge with other experts, and also keep themselves informed through online forums. But they don’t want to stop here – they liaise with other growers in the market who are interested in dividing different cultivation processes between them so as to increase productivity and boost their role in contemporary food production. Fungi have great potential, because they can grow on sawdust, straw, and waste from other industries, prompting us to consider how “we could do things differently in the face of the environmental crisis.”
Gobnjak keeps various fungal cultures in cold storage. The cultures are sourced from certified sellers, but for their experiments the Gobnjak team will also go foraging in nature. The first step is growing a culture in a petri dish. The culture is transferred to a liquid medium, where it continues to multiply and form mycelium. Using a syringe they transfer the mycelium from the liquid to the grain medium. When the grains are overgrown with mycelium, the spawn is ready for inoculation of the fruiting substrate, in this case beech sawdust. In the course of the process any accessories have to be sterilized with a steam sterilizer and sterilizers in the form of 200-litre steel drums in which they sterilize sawdust bags. Every move is made under a current of sterile air, which requires a laminar flow hood, a device that filters dust particles to prevent contamination and potential failures in mushroom growing.
Substrates colonized with mycelium are packed in a plastic bag and under the right conditions the crop will soon peek through. The bags can be labelled with a plastic sticker and sold as grow kits, or they can be transferred to the moist nursery where they grow fresh mushrooms, which they sell or process. When they have harvested the mushrooms, the spent mushroom substrate is decomposed into excellent compost. The only problematic waste is plastic bags (however durable they may be), which they collect for recycling. They make between 60 and 120 bagged substrates per week.
Gobnjak sell what they produce – fresh mushrooms, mushroom powder, and mushroom tinctures. Landowners can make good use of plug spawn. Gobnjak is best known for selling mushroom grow kits for pearl (Pleurotus ostreatus) and king oyster mushrooms (Pleurotas Eryngii), lion’s mane (Hericium erinaceus), shiitake (Lentinus edodes), reishi (Ganoderma lucidum), pink oyster (Pleurotus djamor) and other mushrooms. They can even grow the coral tooth fungus, which is protected in Slovenia. Katarina got it from a member of the Škofja Loka mushroom society and brought it to Gobnjak, where Rok isolated the culture from the mushroom. In addition to culinary and medicinal uses mushroom cultivation benefits the ecosystem, as it helps maintain protected species on forest sites (e.g. Ganoderma lucidum, Hericium erinaceus, Hericium coralloides).