Newswise – With cruelty-free dairy products and compelling vegetarian meat substitutes already on the market, it’s easy to see how biotechnology can transform the food industry. Advances in genetic engineering allow us to use microorganisms to create cruelty-free products that are healthy for consumers and healthier for the environment.
One of the most promising sources of innovative foods is fungi – a diverse kingdom of organisms that naturally produce a wide range of tasty and nutritious proteins, fats, antioxidants and taste molecules. Chef and bioengineer Vayu Hill Mainia life sciences affiliate at Lawrence Berkeley National Laboratory (Berkeley Lab), is exploring the many possibilities for new flavors and textures that can be created by altering genes already present in mushrooms.
“I think it’s a fundamental aspect of synthetic biology that we benefit from organisms that have evolved to be really good at certain things,” said Hill-Maini, a postdoctoral researcher at UC Berkeley in the Bioengineering Laboratory- Experts | Jay Keasling. “What we’re trying to do is study what the fungus produces and try to somehow tap into it and improve it. And I think that’s an important aspect because we don’t need to introduce genes from completely different species. We’re looking at how we can put things together and unlock what’s already there.”
In her most recent work published today in Nature communicationHill-Maini and colleagues from UC Berkeley, the Joint BioEnergy Institute and the Novo Nordisk Foundation Center for Biosustainability studied a multicellular fungus called Aspergillus oryzae, also known as koji mold, which has been used in East Asia for centuries to ferment starch into sake, soy sauce and miso. First, the team used CRISPR-Cas9 to develop a gene editing system that can make consistent and reproducible changes to the koji mold genome. After building a toolbox of edits, they applied their system to make modifications that emphasize the mold as a food source. Hill-Maini initially focused on increasing the mold’s production of heme—an iron-based molecule found in many life forms but most commonly found in animal tissue, which gives meat its color and distinctive flavor. (A synthetically produced plant heme also gives the Impossible Burger its meat-like properties.) Next, the team increased production of ergothioneine, an antioxidant found only in mushrooms that has been linked to cardiovascular health benefits.
After these changes, the once white mushrooms turned red. With minimal preparation—removing excess water and grinding—the harvested mushrooms could be formed into a patty and then fried into a tempting-looking burger.
Hill-Maini’s next goal is to make the mushrooms even more attractive by tweaking the genes that control the mold’s texture. “We think there is a lot of room for exploring texture by varying the fibrous morphology of the cells. Therefore, we could potentially program the structure of the batch fibers for longer, which would allow for a more flesh-like experience. And then we can think about improving the lipid composition for better mouthfeel and better nutrition,” said Hill-Maini, who was a fellow at the Miller Institute for Basic Research in Science at UC Berkeley during the study. “I’m really excited to see how we can continue to study the fungus and, you know, tinker with its structure and metabolism for food.”
Although this work is just the beginning of the journey to harness fungal genomes to create new foods, it demonstrates the enormous potential of these organisms to serve as easy-to-grow protein sources that circumvent the complex ingredient lists of current meat substitutes and the likes of cost barriers and technical difficulties the introduction of cultured meat. Additionally, the team’s gene editing toolkit is a major advance for the entire field of synthetic biology. Currently, a wide variety of bioengineered products are produced from genetically modified bacteria and yeasts, the single-celled relatives of fungi and molds. However, despite humanity’s long history of domesticating mushrooms to eat directly or to make staple foods like miso, multicellular fungi have not yet been exploited to the same extent as genetically engineered cell factories because their genomes are far more complex and have adaptations that support gene editing make it a challenge. The CRISPR-Cas9 toolkit developed in this article lays the foundation for easy editing of koji mold and its many relatives.
“These organisms have been used to produce food for centuries and are incredibly efficient at converting carbon into a variety of complex molecules, including many that would be difficult to produce using a classic host such as brewer’s yeast or brewer’s yeast.” E. colisaid the lead author Jay Keasling, senior scientist at Berkeley Lab and professor at UC Berkeley. “By tapping into koji molds through the development of these tools, we are unlocking the potential of a vast new set of hosts that we can use to produce food, valuable chemicals, energy-rich biofuels and medicines. It’s an exciting new avenue for organic production.”
With his culinary background, Hill-Maini wants to ensure that the next generation of mushroom-based products are not only tasty, but also truly desirable to customers, even those with discerning tastes. In a separate study, he and Keasling worked with chefs at Alchemist, a two-Michelin-starred restaurant in Copenhagen, to experiment with the culinary potential of another multicellular fungus: Neurospora intermedia. This mushroom is traditionally used in Indonesia to produce a staple food called oncom by fermenting waste products left over from the production of other foods such as tofu. Fascinated by its ability to convert leftover food into protein-rich food, the scientists and chefs studied the fungus in the Alchemist test kitchen. they discovered N. intermediate produces and secretes many enzymes during its growth. When grown on starchy rice, the fungi produce an enzyme that liquefies the rice, making it intensely sweet. “We developed a process using just three ingredients – rice, water and mushrooms – to create a beautiful, striking orange mash,” Hill-Maini said. “This became a new dish on the tasting menu that utilizes the chemistry and color of mushrooms in a dessert. And I think what it really shows is that there is an opportunity to bridge the lab and the kitchen.”
Hill-Maini’s work on gene editing research described in this article is supported by the Miller Institute at UC Berkeley. Keasling’s laboratory is supported by the Novo Nordisk Foundation. Both received additional support from the Department of Energy (DOE) Office of Science. The Joint BioEnergy Institute is a DOE bioenergy research center managed by Berkeley Lab.
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