Using CRISPR-Cas9 to Gene Hack Edible Mycelium Into Meat Substitutes

Mushrooms Mycelium To Replace Meat

Many recent efforts have been made to cultivate meat in labs to reduce the ecological and climate consequences of raising cattle. However, these efforts have so far been met with limited results, partly due to the costs and technical difficulties of growing meat in an artificial setup.

An alternative is creating an animal-free meat substitute. And for this to work commercially, the closer to meat, the taste and texture, the easier it is to convince consumers.

So far, most substitutes have been plant-based, like Impossible Foods burgers.

Source: Save On Foods

However, it has been difficult to fully replicate the feeling and taste of real meat with plant-based alternatives. Vegetarian and vegan cooks know that mushrooms are often a good substitute for meat in classic recipes.

And researchers are now looking at genetically modifying mushrooms to make them much more meat-like.

Making Mycelium Taste Meat-Like

Leveraging Established Traditions

Researchers at the University of Berkeley, California have looked at a mushroom/mold already used for centuries of food production in Asia: Aspergillus oryzae, or koji mold. It is the key ingredient in producing key parts of Asian cuisine like miso, sake, and soy sauce.

Previously, the team had already worked on Neurospora intermedia, a fungus traditionally used in Indonesia to produce a staple food called oncom. They used it to create an entirely new dish:

 “We developed a process with just three ingredients – rice, water, and fungus – to make a beautiful, striking orange-colored porridge”

Using fungi's mycelium could bring a lot of advantages compared to meat. Most fungi are healthier food than both plants and meat, with positive effects on cancer prevention, cardiovascular diseases, metabolic disorders, etc.

They are also very efficient at converting organic matter into edible food, including from agricultural waste, wood, etc.

Lastly, contrary to plant-based substitutes, mycelium can be directly made into meat-like patties without the need for extensive processing, protein purification, or ingredient addition. Instead, the only processing needed is removing excess liquid from the biomass prior to grinding and cooking.

Using CRISPR To Create Novel Food

CRISPR-Cas9 has for now mostly been discussed in the context of gene therapy, with the first treatment approved at the end of 2023, something we discussed in our article “Sickle Cell Disease Gene Therapies Approved by FDA Highlighting Potential of CRISPR/Cas9 Technologies”.

CRISPR can be used for many other applications that require adding or modifying the genetic makeup of an organism. The team of Jay Keasling at Berkeley started to do a series of genetic modifications of koji mold, using CRISPR-CAs9, to make it taste like real meat:

• They made the mold produce a large amount of a molecule called heme (like in HEMoglobin), which gives meat its color and flavor.
• Then they added the production of ergothioneine, an antioxidant only found in fungi that is associated with cardiovascular health benefits.

Source: Nature.com

This resulted in reddish fungi, which when removing some of the water content can be shaped into a burger patty and fried the same way.

Source: Nature.com

The edible mycelium CRISPR toolkit is described in detail in the scientific paper “Edible mycelium bioengineered for enhanced nutritional value and sensory appeal using a modular synthetic biology toolkit” published in Nature Communication.

In it, they describe that the modified koji mold has “the highest levels of intracellular heme in the fungal mycelium and a rare example of heme biosynthesis engineering in filamentous fungi”.

Next Step To Make Mycelium-Based Meat

While close to the intended results, the koji mold patty is not yet perfect. The researchers are already looking at the next steps to make it even more similar to meat:

• Improving the texture, by making the mycelium fiber longer so it has a more meat-like feel when eating.
• Improving the lipid composition, to make it both healthier and more pleasant in the mouth.
• Further adding or increasing the concentration of functional ingredients that are key to medicinal mushrooms health benefits used in traditional medicine, like reishi, shiitake, lion’s mane, maitake, etc.

The CRISPR toolkit developed for this research could also be applied to other edible mushrooms, with such mushrooms preferable to more exotic or industrial species, as they have a long history of consumption by humans and a known chemical, nutritional, and safety profile.

Companies Selling Mycellium-Based Meat Substitute

1. Eat Meati

The company uses non-genetically modified mycelium to produce mycelium-based meat substitute.

Source: Meati

They use MushroomRoot (N. crassa mycelium), which can be found in nature in the burned areas left in the wake of wildfires. The CRISPR-Cas9 toolkit developed in Berkeley could likely be adapted to modify N. crassa mycelium as well.

2. Untamed Feast

This mushroom-focused company mostly sells mushroom extract, dried mushrooms, and ready meals with mushrooms as diverse as morels, porcini, chanterelle, and Chaga.

Source: Untamed Feast

It is also selling “Mushroom Meat“, a meat substitute for burgers based on a mix of wild mushrooms (porcini, boletes, shiitake, oyster, agaricus, chaga) as well as soybean protein, rice flour, seaweed, and cornstarch.

3. Prime Roots

This company already uses koji mold to produce meat-like products, including deli meats, charcuterie (salami, pepperoni, pizza-style pepperoni, apple-sage and black truffle patês, and foie gras torchon) and bacon.

Source: Prime Roots

Considering the company already uses koji mold for making meat substitutes, it is obvious that the Berkeley research could have direct application to their products and represent the next step for the company.

This could be done either through direct collaboration or through replicating the R&D and adapting it to their own koji mold strains and manufacturing processes.

Conclusion

Healthy meat-like alternative foods that require fewer resources but provide the same taste are likely to become a big business if the economics of their cultivation make sense. Plant-based and lab-grown meats are good options but face respectively the hurdles of complex processing and high-cost structure.

In contrast, fungi mycelium grow well in lab and industrial conditions and have been used for millennia in many fermentation processes to produce dough, beer, sake, miso, soy sauce, etc.

With the emergence of new genetic engineering tools like CRISPR, it is now realistic to expect mycelium to achieve parity with “real” meat in texture, flavor, color, etc. in the next few years.

In addition to tasting the same as ground beef, a fungi-based meat product is likely to be a lot healthier, bringing high levels of antioxidants and other health-promoting molecules to the consumers' diet.

Lastly, such cultivation methods will be very useful to recycle farming wastes, grow food in areas with limited space like urban farms, or even to feed astronauts living in permanent settlements on the Moon and Mars (something we discussed in “Space Food – How Will We Feed Humanity’s Next Wave of Pioneers?”).