Penn State researchers have aided the state’s important mushroom industry for nearly 100 years, and they’re still going strong. But mushrooms aren’t just for eating anymore.
Pennsylvania grows almost two-thirds of all white button mushrooms produced in the United States, and Penn State’s leadership in research and education has shaped and supported the industry since its beginnings. In recent years, however, mushroom-related research at Penn State has expanded across departments and even colleges into new and surprising areas, from food science to environmental clean-up to architecture and design.
Back in 1980, when Mark Wach arrived in University Park, it didn’t take long for him to fall under the spell of mushrooms. Armed with a degree in biology from the University of California at Berkeley, Wach had come east for graduate work, drawn by Penn State’s reputation, and quickly hit it off with Charles “Pete” Romaine, the plant virologist and mushroom expert who would become his adviser.
“Once I saw that first crop of mushrooms growing out in the Mushroom Research Center, I was hooked,” he remembered. “You either love them or you can walk away. There’s no in-between.”
Wach loved mushrooms enough to stay and earn a doctorate. He went on to become chief innovation officer at Sylvan Inc., a Pennsylvania-based company that is the world’s largest producer and distributor of mushroom spawn, and president of the International Society for Mushroom Science. And he recently concluded a term as president of the Penn State Agricultural Council, a group of industry leaders that serves in an advisory capacity to the dean of the College of Agricultural Sciences.
Wach’s enduring ties to Penn State are a living example of the industry partnerships that embody the University’s land-grant mission. Perhaps no such partnership has been stronger or more effective across the decades than the one created to further the commercial growing of mushrooms.
Mushrooms, and specifically the common white button mushroom, Agaricus bisporus, are big business in Pennsylvania. The state grows almost two-thirds of all Agaricus produced in the United States, most of that coming from farms in Chester and Berks counties, with ground zero at Kennett Square, the self-proclaimed “mushroom capital of the world.” Penn State’s leadership in research and education has shaped and supported the industry since its beginnings.
“We are the only academic institution in the United States that has a facility dedicated for cultivated mushroom research,” said John Pecchia, associate professor of plant pathology and manager of the Penn State Mushroom Research Center. The center is housed in a long, low building on the north end of campus that holds nine climate-controlled growing rooms, a spawning-casing area and a state-of-the-art composting facility.
Here Pecchia and David Beyer, who holds the enviable title of professor of mushrooms, lead a research and extension effort that encompasses all aspects of mushroom cultivation, pathology and production. In November 2023, a team led by Beyer was awarded a $7 million grant from the U.S. Department of Agriculture to develop new pest management tools for mushroom crops and create new outreach opportunities engaging growers, farm owners, residents and policymakers.
In recent years, however, mushroom-related research at Penn State has expanded, fungus-like, across departments and even colleges into new and surprising areas, from food science to environmental clean-up to architecture and design. Mushrooms are not just for eating any more.
Mushroom research at Penn State began in earnest in the fall of 1925, when Charles A. Thomas, a newly hired “economic entomologist” at the Bustleton field station near Philadelphia, began experimenting on insect pests using quart milk bottles filled with mushroom spawn.
Spawn, effectively the seed by which mushrooms are commercially propagated, consists of sterilized cereal grain — millet, rye and sometimes wheat — inoculated with mycelium, the mushroom’s thread-like root matter. Once the grain is well-colonized, the spawn is mixed into a bed of nutrient-rich compost, covered with a casing layer and left to grow in the dark, under temperature- and moisture-controlled conditions. In two to three weeks, the fruiting bodies — the familiar round white caps, in the case of Agaricus — emerge through the casing.
In the early days of the industry, the stuff inoculated with mycelium was usually a brick formed of horse manure. By 1930, however, inconsistent yields led Penn State plant pathologist James Sinden to begin experimenting with cereal grains as a possible alternative. “The mycelium from the new medium immediately grew faster and more vigorously,” Sinden later wrote, “so that within a week I was convinced that it had advantages over the other spawn.”
The Sinden Grain Spawn method, first patented in 1932, “really started the industry rolling,” Wach said. Almost all commercial spawn is now produced by this method.
An important offshoot of Sinden’s trials was the establishment of the Mushroom Spawn Lab, a collection that today contains nearly 300 strains of Agaricus bisporus, as well as more than 200 other mushroom species and a collection of over 340 different disease strains applicable to mushroom cultivation. Housed in Buckhout Lab, these resources are made available to researchers and growers around the world.
In 1956, Sinden’s successor, Leon Kneebone, developed the Mushroom Short Course, an annual two-day education program that gives growers from all over North America a chance to share their experiences while learning about the latest advancements in production practices and disease prevention. The 63rd Short Course was held in Kennett Square in 2022. Beyer and Pecchia now plan the course curriculum, based on input from growers.
Yet another key Penn State contribution occurred in the early 1970s, when professor of plant pathology Lee Schisler and his graduate student David Carroll invented and patented SpawnMate, a delayed release fertilizer for mushroom cultivation that boosted yields by up to 60%.
“It really revolutionized the industry,” Beyer said. “Its application became standard practice and has resulted in significant increases in yield around the world.”
The issues facing commercial growers today are a mix of old and new. At the top of the list is a worsening labor shortage.
“All of the mushrooms harvested for fresh quality in the U.S. are still pretty much harvested by hand,” Pecchia said. “The houses are emptied by hand, the rooms are cleaned and watered by hand — all the packaging, too. It’s hard work, and it’s very, very labor intensive.”
Maintaining a labor force has always been a challenge for the industry, he said.
“In the last few years, it’s become much worse, and this in turn leads to other problems. When you’re short on labor, you start cutting corners, and you end up with lesser quality and increased disease,” said Pecchia, who is leading a USDA-funded interdisciplinary team looking at strategies to address this issue, including labor-saving growing practices, automated packaging, and a robotic harvesting technology.
Of more recent concern is a scarcity of peat moss. As Pecchia explained, growers have traditionally used peat moss as a casing material, placing it on top of the inoculated compost to hold in moisture and regulate pH during the growing phase. Over the years, he said, other substances have been tried, but “nothing has ever been found to work as well or to be as cheap.” Unfortunately, the supply of peat moss has dwindled sharply, and there is rising concern over how much longer Canadian peat bogs, the major supplier, can be sustainably harvested. Beyer and a graduate student are currently working with industry to screen possible alternatives.
Pests and diseases are an ongoing challenge. Various fungal pathogens, insect pests, a bacterial blotch and viral diseases all affect mushrooms, their presence rising and falling with environmental pressures. Beyer recently applied for a large grant to continue his work on disease control, and he has combined with Steve Haines, teaching professor of information sciences and technology, to develop Cropsmarts, a suite of mobile apps that helps growers monitor environmental conditions and indicators of disease.
About 10 years ago, the phorid fly, a tiny pest that had previously been well-controlled, became a giant headache, with dense swarms of the insects descending on hapless homeowners living in the vicinity of Chester County’s mushroom farms. Approached by local elected officials, Beyer recruited a team of Penn State entomologists led by distinguished professor Tom Baker, senior research associate Nina Jenkins and assistant research professor Mike Wolfin, who studied the problem and eventually came up with a solution, adapting a capture-and-kill technique they had developed to combat malaria-carrying mosquitoes in Africa.
For both Beyer and Pecchia, collaboration is an essential component of problem-solving.
“Our approach has been, if we can’t do it ourselves, we know where to find the right expertise at Penn State,” Beyer said.
In recent years, mushroom-related research at the University has expanded beyond the challenges of commercial cultivation. In the early 2000s, for example, Pete Romaine, then holder of the John B. Swayne Chair in Mushroom Biotechnology, pioneered the use of transgenic mushrooms as “biofactories” for producing pharmaceuticals.
Robert Beelman, emeritus professor of food science, has been working for 15 years to understand and promote the nutritional value of mushrooms. Much of his attention has gone to ergothioneine, an amino acid with powerful antioxidant properties that is present in much higher concentrations in mushrooms than in any other food source. Although direct causation has yet to be proven, epidemiological research conducted by colleagues at Hershey Medical Center suggests that ergothioneine may have protective effects against diseases of aging, including Alzheimer’s and Parkinson’s, as well as cancer.
A study led by Charles Anderson, professor of biology, points to yet another role for mushrooms. The project’s rather sobering goal is to identify potential sources of food in the wake of a global catastrophe — an event on the scale of an asteroid strike or a nuclear war. Such an event would fill the upper atmosphere with particulate matter, darkening the Sun and making traditional agriculture all-but impossible.
“But we have calculated that the calories embodied in the inedible plant biomass that exists on the Earth right now would be enough to feed the planet for at least 100 years,” Anderson said. “The challenge would be to make that biomass digestible.”
That’s where mushrooms, the great decomposers, come in. In a preliminary study, with Pecchia’s help, undergraduate honors student Hannah Klatte found that growing mushrooms on woody biomass — in this case, willow chips — can make it easier to break down that biomass to its component sugars, which can then be converted into food. As a bonus, the process also yields edible mushrooms.
“And all of this is happening in a way that doesn’t require sunlight,” Anderson noted.
Absent a sudden disaster, this same digestive prowess holds promise for environmental clean-up.
“Certain types of fungi produce enzymes that can break down plastics, which are essentially complex carbohydrates,” said mycologist Josephine Wee, an assistant professor of food science. Wee is working with engineers in the plastics program at Penn State Behrend to investigate the possibilities.
As a microbiologist, Wee seeks to connect genetic differences with their consequences for the structure and function of an organism.
“There are so many known species of fungi,” she said. “I’m interested in what genes make some species better at producing toxins, while others produce more protein, or grow with a certain structure or texture. How can we select for the genes to get the properties we want?”
In 2021 she was awarded a seed grant from Penn State’s Institutes of Energy and the Environment to identify strains of mycelium that might work best as a “scaffolding” for growing meat, not on the farm but in the lab.
“You take cells from an animal, through biopsy or stem cells, add them to a medium, and grow them over time into tissue that resembles meat,” Wee explained. Floating in medium, these adherent cells need a platform, or scaffold, to grab onto as they grow. “Mycelium is a really good candidate for this because it’s cheap and biocompatible. And if you look at it under a microscope it has fibers that look like meat.”
Wee, who serves on the judging panel for the XPRIZE Foundation’s $15 million “Feed the Next Billion” competition, said cellular agriculture will be critical for global food security, particularly where growing populations lack access to farmland, and that fungi including mushrooms have an important role to play.
“Humans have been eating fungi for a long time,” she said, “but in this sense mycelium is a food of the future.”
Perhaps the fastest growing area of mushroom-related research envisions mushrooms, more specifically mycelium, as a living material, suitable for applications ranging from building construction to designer handbags — maybe even computer chips. A workshop held on the University Park campus in the spring of 2022 explored the state of the art in “fungal biomaterials.” Benay Gursoy, assistant professor of architecture in the Stuckeman School with an academic background in computational design and fabrication, was one of its organizers.
“One of the things we like to do in my lab is to make our own materials and then explore what we can do with them,” she said. In a class she calls “Hacking Materials and Production Methods,” she and her students decided to experiment with mycelium-based composites in 2018. “We learned to make bricks from mycelium, bricks that self-heal but also do not require mortar because they grow into each other."
One of her students, Ali Ghazvinian, subsequently decided to work with these composites for his doctorate.
Why mycelium? Traditional building materials account for some 40% of global carbon emissions, Gursoy noted, and the race is on to find better alternatives.
"(Mycelium) has become a hot area for designers and architects because it’s sustainable and low-cost,” she said. “From a design perspective, these are materials that you can grow on agricultural waste or cardboard, and at the end of their life cycle, they’re biodegradable.”
With Pecchia’s help, Gursoy and her students have developed an entire line of research around mycelium.
Ghazvinian began by exploring structural and mechanical properties. Using computational design techniques, he designed and built a room-sized structure of 64 load-bearing mycelium bricks. Another doctoral student, Alale Mohseni, adapted an extruder tool and robotic arm used for 3D printing of clay to allow 3D-printing with a paste made of mycelium — eliminating the need for molds and opening new possibilities for complex shapes. Natalie Walter, a former master’s student, grew acoustic panels from various mycelium composites and tested their acoustic absorption properties with an eye toward architectural applications.
Gursoy and her students are also collaborating with Felecia Davis, associate professor of architecture in the Stuckeman School, and one of her former doctoral students, Farzaneh Oghazian, on a hybrid system, growing mycelium composites on a framework of knitted textiles. The idea, dubbed Mycoknit, is to combine the compressive strength of the mycelium with the tensile strength of the fabric to create low cost, biodegradable architectural structures.
“Working with living materials requires a different way of thinking about the design process, one in which you have to work with the material itself and understand what it wants to be,” Gursoy said. There are unique challenges, from the added time required to grow the components you want to the ever-present threat of contamination. Scaling up is no simple matter, either. “It’s not easy to make big things, like casting concrete. You have to think about how it can breathe, how it can get oxygen at its core.”
The next steps, she said, “in order to take the research further than the hype,” will require a rigorous interdisciplinary approach. But Penn State has the intellectual resources and the facilities to accomplish this, she believes, starting with its one-of-a-kind Mushroom Research Center.
“We could not have done any of this without John [Pecchia]’s help, and his openness to collaborating with us,” Gursoy said.
For Pecchia’s part, it only makes sense to share the wealth. His doctorate from Penn State in plant pathology 25 years ago focused narrowly on the science of composting, specifically composting for growing mushrooms. Since then, he has broadened his knowledge to include all aspects of mushroom cultivation. Over the years, Pecchia said, he and Beyer have been quick to reach out to whichever Penn State expert they needed to solve the problem at hand and help growers.
“That’s kind of what we do,” he said.
More recently, he said, “People like Benay have been reaching out to us. I definitely didn’t foresee this 10 years ago, but I’m not sure it’s a surprise. There’s a lot of interest out there, and a lot of innovative ideas. It’s almost anything and everything mushroom anymore. And we’re in the position to help.”