Controlled environment agriculture is NOT exclusive to leafy greens. The term CEA could as easily be applied to the environment required to grow a wide range of edible mushrooms with added health benefits.
It seems to be a different type of farmer that grows mushrooms, but essentially the skills are an extension to planting a seed in a substrate on a shelf, then controlling and monitoring the temperature, humidity, airflow and lighting schedule until harvest. The difference is that the seed is a spore and you inoculate the substrate with the tiniest involvement of water. The life cycle of the crop can vary but once cropping begins, several flushes of mushroom fruiting are possible.
Of course other mushrooms may take slightly longer but with energy costs rising fast, growing high value medicinal mushrooms could be an additional revenue for CEA farms with an easy adaptation of current farming technology. Dare I say it, switching off the lights to save energy to get farms through lean periods isn’t the worst idea either.
‘Right tech for the market’ —Chris Higgins
Mushrooms belong to the kingdom of fungi, which is separate from plants and animals. They are part of a huge 100,000 range in species. Approximately 2000 of these mushrooms are edible and more than 500 can be described as having significant health benefits. Wow, how many do you eat or even have access to? I know my larder was limited until I discovered their anti-inflammatory and nutritional value.
The most cultivated is the common button mushroom (Agaricus bisporus) often referred to in its mature state as the portobello mushroom (now called Agaricus brunnescens). This white chestnut mushroom is commercially produced, and the one most often seen on our grocery shelves. Only if you veer off into a specialist shop can you see an alternative range on offer including Oysters of all colors, and Shiitake. Many are not yet mainstream but we hope to highlight why you should grow these in CEA.
One reason is that the global medicinal mushroom market is strong and expected to grow to 6,870.7 Million USD during the forecast years 2022-2030. Secondly mushrooms are a good alternative source of protein if you are vegetarian, and are low in fat and high in vitamins and minerals.
Medicinal mushrooms and health benefits
The first significant recognition of medicinal properties in mushrooms began with Alexander Fleming’s discovery of Penicillin in 1928. The discovery led to the Nobel prize in 1945 – but it might never have been noticed, since it was only by chance that cultures were left on an open bench and a mold spore infected the medium. Penicillin is the world’s most common antibiotic, most commonly prescribed as amoxicillin to treat a wide range of bacterial infections. Almost all edible mushrooms will have inherent antibiotic and anti-inflammatory properties.
Since ancient times mushrooms have been used for their medicinal properties, particularly in Japanese and Chinese cultures. Europeans knew of these benefits too. DNA extracted from Otzi the iceman, found buried in a glacier 5000 years ago revealed he had two mushrooms with him while navigating the Alps. Birch polypore, better known as hoof fungus (Fomes fomentarius) may have been in his possession to help combat parasites but most likely he used it for tinder (amadou, the dry cork-like inner is commonly used in fly fishing to aid buoyancy). Hoof fungus (which sounds pretty unappetising) is mentioned by Hippocrates for dressing wounds, in Chinese medicine to treat cancers, and in Indian medicine as a diuretic, laxative, and relaxant. Recent studies show extracts have a significant modulatory effect on drug-resistant breast cancer cells.
If you begin to research medicinal mushrooms one of the leading mycologists, Paul Stamets, is perhaps the starting point. Stamets tells a heartfelt story about his mother Patty who survived breast cancer after taking Turkey tail extracts, which appeared to accelerate her immune recovery post-radiotherapy. Stamets, whose profile was raised by the Netflix film ‘Fantastic Fungi’, has dedicated his life to the research of important medicinal mushrooms. In Asia more than 100 varieties of mushroom are used to treat cancer – but how do you know which ones to grow for the best value and the greatest health benefits?
Let us share with you why you should grow these in CEA
In 1993, Japanese researchers showed extracts from Lion’s mane could stimulate nerves to regrow. The findings could have implications in the treatment of Alzheimer’s and other neurodegenerative diseases. Active compounds in Lion’s mane mushroom can help promote neurogenesis and enhance memory, a new study reports. This is because Lion’s mane is high in nerve growth factor, important for the myelin sheath that surrounds nerve fibers. It’s an important discovery which could lead to a breakthrough in the treatment of Multiple Sclerosis and many other diseases.
Ganoderma lucidum, a red variety of Reishi (Japanese for Divine), is a polypore fungus native to East Asia that belongs to the genus Ganoderma. Its reddish brown varnished kidney-shaped cap with bands and peripherally inserted stem gives it a distinct fan-like appearance. This mushroom cannot be consumed fresh, but must be dried after harvest and then marketed. Other members of the genus may have different medicinal properties and although less mainstream, more availability of these cultures will help increase biodiversity in this space.
The health benefits of Reishi have been widely demonstrated and with known anti-cancer properties it is not surprising it is widely used in Asian alternative medicine. Reishi contains over 400 different bioactive compounds including Beta-glucans. Research shows promise in altering inflammatory pathways in white blood cells, switching on natural killer cell genes which help fight infection and cancer.
One of the most colorful mushrooms, Turkey tail increases lactobacillus and bifidobacterium, both probiotics that decrease dangerous bacteria including E Coli, shigella, clostridium and Staphylococcus Aureus. Polysaccharide-K (PSK) or krestin, from T. versicolor, is an approved mushroom product in the treatment of cancer in Japan. There is evidence that PSK in Turkey tail improves 5 year survival rates in gastric and colon cancer, though only at less advanced staging.
Enoki (Flammulina velutipes) mushrooms are an interesting choice because they fruit in winter and need very little light to grow. I’ve eaten these in a traditional Japanese Shabu Shabu where they taste amazing cooked in a light soy broth.
Some cultures have long associations with mushrooms: epidemiologists found farmers who grow and eat enokitake in Nagano prefecture in Japan have a 40% lower incidence of cancer-related mortality. Although Lentinan from Shiitake mushrooms increases the survivability from stomach, prostate, colorectal and liver cancer, you should cook Shiitake mushrooms for longer to avoid potential negative effects from high doses.
Cordyceps are a source of a wide range of nutraceutical and medicinal metabolites. Recent studies suggest it may have anti-aging effects, most likely due to its anti-inflammatory properties. They are actually quite a rare mushroom, leading to a high market value. Various commercially viable culture methods have been established, depending on the type of Cordycep grown. Our friend Huan Shuma in Peru has kindly allowed us to share his liquid culture development of Cordyceps militaris grown on an organic brown rice substrate. The strain was sourced from leading Cordyceps expert Ryan Paul Gates’ from Terrestrial Fungi.
Images of different stages of growth in Cordyceps Militaris courtesy of our friend Huan Shuma from @chavinherbalists
Starting cultures like this requires a degree of skilled sterile culture technique and the appropriate technology. Many of us in the plant tissue culture world will have the ability to adapt our skills and equipment. Creating a bank of initiates from spores can take some time to get clean but after this stage you can inoculate either sterilized substrates or wooden dowels that are then drilled into preferential tree stumps.
Mushrooms can grow easily in a controlled environment
I have grown the easiest of these mushrooms, the blue Oyster (Pleurotus ostreatus) on a coffee waste substrate (main image). It was so simple. No inoculation is required in pre-prepared kits and it gives you a good feel for the right conditions before you start investing further. The taste was satisfying, added to by the pleasure of having grown it myself.
The medicinal mushrooms we have described – Oysters, Enoki, Shiitake, Cordyceps, Reishi and Turkey tail – can be farmed in CEA. Each variety needs a particular temperature to thrive, and this varies throughout the growing cycle. Pink Oyster mushrooms, for example, prefer a temperature of around 80 F which makes them more attractive to warmer climate/seasonal growers. Other Oysters fruit at cooler temperatures – anywhere from 40-70 F – which could be a seasonal shift depending on the market being served.
Temperature plays a vital role in the quality of mushrooms; the optimum is anywhere between 65-75 F for the development of the majority of mushrooms. Above this temperature, mushrooms might get too dry. They love a humid, damp environment. Monitoring moisture levels during the cultivation period is vital for continuous harvests. HVAC in isolated rooms is needed for commercial cycles, and many farms use shipping containers which offer flexibility and isolation.
Log culture (where spawn-inoculated dowels are pushed into logs) was developed more than a millennium ago, and is still used today. The majority of mushrooms we have described are wood-loving species which are happy to grow on sawdust, straw or other high-lignin substrates. These are often readily accessible waste products. The main exception is Cordyceps, which requires a more specialized substrate that replicates its insect host.
Mushrooms require light only when developing fruit from mycelium. As a general rule, a few hours of dim light is sufficient for mushrooms to develop their edible fruiting bodies, also called ‘pinning’ – as in the image above.
Buying ready-made substrate such as the above already inoculated with spawn can save time. Spawn can be delivered in a variety of forms, including liquid inoculate, or grain which is typically used by commercial cultivators. This overcomes the issue of maintaining viable spawn in cultures which can be time-limited to a matter of months in refrigerated condition.
As they start to grow out, with mycelium pushing forward, the substrate becomes dense in carbon dioxide levels. Some, like Reishi, need very high CO2 levels (up to 40,000 ppm) during the early ‘antler’ stage under condensing fogging environments for high humidity. According to Dr Ghilavizadeh most mushrooms require a CO2 level of around 1000 ppm (remember the ambient level is 421 ppm).
Low intensity LEDs are ideal to stimulate growth when mushrooms are grown indoors. Oyster, Shiitake, and Reishi all demonstrate strong photosensitivity. Blue light is an important environmental factor that induces mushroom primordial development and fruiting bodies in Oysters. Shiitake are also known to produce primordia with low light levels (10.5 μmol/m2/s) in the blue range (peak 455 nm). Other studies suggest red and blue LEDs can increase biomass. More research in CEA will provide better insights for farmers on both spectrum and light intensity at different developmental stages in cultivated mushrooms.
From what we can establish from Paul Stamets’ book, Oyster primordial formation needs around 750-1500 lux and fresh air exchange every 4-8 hours. Reishi primordia (antler) stage needs 4-8 hrs at 200-500 lux increasing to 500-1000 lux at conk and the final fruiting stage requires 750-1500 lux for 12 hrs/day. Reishi is slow growing and will crop twice in 90-120 days depending on ideal conditions.
Harvesting your mushrooms
Dr Ghilavizadeh advises picking your mushrooms at just the right time. These yellow Oysters are at the right stage for picking. He says ‘the first hand is the harvester and the second hand must be the hand that wants those mushrooms to cook’.
The best time to harvest colored mushrooms is very early in the morning at the peak of their pigmentation. Mushrooms should be stored in a cool place at a temperature of four degrees (39.2F) immediately after harvest to maintain their durability prior to drying and packaging.
In the Wild
We have described the main mushrooms grown for medicinal properties (excluding magic mushrooms) but there are so many more out there waiting to be discovered and cultured like the cinnamon- and orange-smelling Hericium novae-zealandiae.
Image courtesy of our friend Mike Wallace: Hericium novae-zealandiae (formerly Hericium coralloides) is a saprotrophic fungus, commonly known as the coral tooth fungus. It is a relative of Lion’s mane and has a mushroomy ‘seafood’ taste akin to lobster, I am told.
Taking a culture from spores, Mike grew this coral tooth fungus from the wild. Visible fruiting bodies germinated on sterile culture medium as the hyphae extend out.
Image courtesy of my friend and mushroom forager Maxime Jay of Coeur Sauvage Scotland : Chicken or Hen of the woods (Laetiporus Sp) as it’s known in Scotland. I guess the argument of which is best, wild or cultivated, is dependent on access, knowledge and supply. There is no doubt in my mind, having been out in the Scottish hills with Maxime, that wild mushrooms will always have a niche high-quality market value in food service.
Chaga (Inonotus obliquus)
No account of medicinal mushrooms is complete without Chaga. ‘Superlife’ author Darin Olien’s health regime includes Chaga in his ‘Shakeology’ superfood and as a tea to combat daily stress. It’s a strange hard black fungus with a high melanin content and a surprisingly sweet taste due to vanillin. It has demonstrated some impressive medicinal properties as an immune boosting anticancer agent in lab tests. But be careful, as it also contains high oxalates so is inadvisable for anyone with kidney disease or who is pregnant. It may not be suitable for growing in CEA but I would love to be proven wrong on that.
Rare Cordyceps could hold the key to future medicines
Himalayan Gold: Cordyceps sinesis or Kida Jada (Hindi). Thank you to our friend Dr. Shashank Saini who found these ultra-rare Ophiocordyceps sinesis on a hike at Badrinath district, Uttrakhand, India in the Himalayas. These fungi (technically they are not a mushroom) cannot be farmed despite being valued at more than three times their weight in gold. They are sought after for aphrodisiac effects and also used by some athletes to improve their performance. Cordycepin, the bioactive compound in the fungus, has potential medicinal and therapeutic applications and shows promising cytotoxicity in cancer cells. However, a word of caution, this mushroom can have antiplatelet effects, as it acts as a blood thinner so could increase the risk of bleeding or bruising.
The fungus requires a special environment at 4500 ft altitude and is only found in the Himalayas around the Sino-Indian border and in Tibet. The area is covered with glaciers and the fungus releases endoparasitic spores which infect a caterpillar. During winter the fungus grows out of the insect’s head to form a bud inside the snow and remains frozen until spring. As the glaciers melt in early summer the fruiting bodies (as shown in the figure) grow out of the soil and are harvested by local people.
Check out this never-before-seen video of the fungus and a live caterpillar in Badrinath district, Uttrakhand, India in the Himalayas. Despite Cordyceps scary film debut in ‘The Last of Us’ (based on an action adventure computer game) we can reassure you these fungi are not in evolutionary terms about to take over higher animal species. Instead, with more research they may hold important bio pharmaceutical compounds that aid human health.
Image courtesy of my friend Gloria MacDonald. Wild chanterelles (Cantharellus cibarius) growing wild in the woods beside my home in Scotland. False chanterelle is flatter on top, with less of a forked edge. It is crucial to know what you are looking for as you could have a nasty turn when eating your mushroom pizza if you pick the wrong type.
When foraging in the wild, it’s important to preserve the ecosystem by not over-collecting.
How to eat them?
A different set of skills helps you combine mushrooms in a meal where the medicinal qualities are retained. Whether eaten fresh in a Shabu Shabu or as dried extracts in a tea, there is no doubt medicinal mushrooms have a significant health benefit.
* Cropping information from Paul Stamets’ book ‘Growing Gourmet and Medicinal Mushrooms’. All Images unless otherwise stated are the property of Urban Ag News, please ask for permission to reprint our articles. We thank Brian Harris, Dr Shashank Saini, Dr Ardalan Ghilavizadeh, Ximena Zamacona, Huan Shuma, Mike Wallace, Maxime Jay, Shannon Maas, Gloria Macdonald and Jake Wilson for their contributions to this article.
Despite their popularity, there are potential dangers inherent in consuming mushrooms. Always take advice from a qualified mycologist if you want to add fresh or foraged mushrooms to your diet.
Janet Colston PhD is pharmacologist with an interest in growing ‘functional’ foods that have additional phytonutrients and display medicinal qualities that are beneficial to human health. She grows these using a range of techniques including plant tissue micropropagation and controlled environmental agriculture to ensure the highest quality control.
Unless otherwise stated all images are courtesy of The Functional Plant Company and property of Urban Ag News.