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Making lab-grown meat more sustainable

In the future, ‘circular cell culture systems’ (pictured in this illustration) could use algae-based innovations to minimize the environmental impact of lab-grown meat. Credit: Yuki Hanyu / IntegriCulture Inc.

Lab-grown meat could soon be a readily available source of high-quality protein that negates some of the environmental impacts and welfare concerns of rearing livestock. However, scaling up the production process comes with sustainability challenges of its own.

Making meat in the lab starts with animal cells that are cultured in a nutrient-rich medium. These cells are coaxed to grow into muscle tissue using growth factors. Once the tissues mature, they can then be harvested and processed into meat products.

The path to market has been relatively swift. The first lab-grown burger appeared in 2013; and by 2023 lab-grown meat products were approved for sale in the United States.

But lab-grown meat continues to be reliant on grain to supply key nutrients for the medium; and on foetal bovine serum, a by-product of the meat industry, which contains important growth factors, explains Tatsuya Shimizu, a professor at Tokyo Women’s Medical University’s Institute of Advanced Biomedical Engineering and Science in Japan. Both have significant environmental implications.

For Shimizu and his collaborators, part of the solution could be small, single-celled photosynthetic organisms, known as microalgae.

GOING FOR GLUCOSE

Lab-grown meat typically requires the use of crops to create a culture medium that provides glucose as a source of energy for cells, so it is not entirely environmentally friendly.

Lab-grown meat (pictured) starts as animal cells cultured in a nutrient-rich medium.

“Lab-grown meat will decrease the use of grain that would have been fed to animals and reduce methane emissions from cows,” Shimizu says. However, most of the glucose in traditional culture media for lab-grown meat comes from grains such as corn and wheat, which have an environmental impact. “For example, grain cultivation requires water, fertilizers and pesticides,” Shimizu says.

In contrast, cultivation of microalgae doesn’t require fertilizers and pesticides, and wastes minimal water. It can also occur on land that isn’t suitable for farming, including urban areas. Microalgae could supply glucose that has a much smaller environmental footprint than glucose from grains, argues Shimizu.

His team have been working with two different microalga: Chlorococcum littorale and Arthospira platensis. They have been able to efficiently extract glucose by freeze-drying, and then using acid and heat to create an extract.

Using a different strategy, the team were able to obtain 18 out of the 20 amino acids needed for protein synthesis from extracts of Chlorella vulgaris, a different species of microalgae. When these algae extracts were added to muscle cells in animal studies, they were able to support cell growth just as well as a traditional medium1.

“From an energy efficiency point of view, the energy conversion along each step of the process is 10 times more effective when you use microalgae as opposed to grain,” says Yuki Hanyu, CEO of IntegriCulture Inc, a leading provider of lab-grown meat in Japan, and Shimizu’s collaborator.

WASTE NOT, WANT NOT

Having shown that microalgae can replace nutrients normally supplied by grain, the team began to look at other parts of the process. They quickly realized that if lab-grown meat was to provide protein for even a fraction of the world’s population, the amount of waste generated during its production would be considerable.

In particular, throwing spent culture media away is inherently wasteful, as valuable compounds remain. In Shimizu’s tests, 22% of the glucose in a traditional media was left after three days of culture with mouse muscle cells. Similarly, 60% of the amino acids supplied and 99% of the potassium in the media remained unused. The trouble is that media must eventually be discarded, as it also develops substances that are harmful to cultured cells — primarily ammonia and lactate.

Shimizu and the team again turned to microalgae, but for a different purpose. They found that culturing C. littorale or C. vulgaris microalgae in used media resulted in the removal of up to 80% of the ammonia and 16% of the phosphorus2.

A different approach was required for removing lactate, which is not a metabolite that most microalgae naturally use.

In collaboration with Tomohisa Hasunuma, director of the Engineering Biology Research Center at Kobe University in Japan, the researchers introduced the L-lactate dehydrogenase gene from Escherichia coli into Synechococcus microalgae. This allowed the microalgae to consume lactate in spent media and convert it into pyruvate, a metabolite that can be converted into glucose by cells3.

When this recycled media was reintroduced to previously cultivated mouse muscle cells, the number of cells were found to increase in number by four-fold after three days, showing that it can result in efficient growth of cells4.

“So far, we have succeeded in using the same media over two cycles and are in the process of testing how many times it can be recycled,” says Hasunuma.

GROWTH FACTORS

The last piece of the puzzle — one where microalgae could not help — was supplying the growth factors needed to help the muscle cells grow, including insulin-like growth factors and hepatocyte growth factors. Traditionally, these are supplied to lab-grown meat by foetal bovine serum, which, as the name implies, comes from the blood of cow foetuses. The serum is a by-product of the meat industry, but the use of foetuses raises ethical concerns.

Today, animal cells grow into lab-grown meat in a grain-based media (red). However, an algae-based media being developed in Japan would likely lower the greenhouse gas emissions associated with producing lab-grown meat at scale.

Instead, Shimizu collaborated with IntegriCulture to use conditioned media. This is a cell culture media that has been incubated with cells from livestock organs, such as livers or placentas, that secrete the required growth factors into the media — avoiding the use of foetuses.

“This also eliminates the need for purification typically associated with growth factors derived from other sources, which makes it more efficient,” explains IntegriCulture’s CEO Hanyu. Together with the microalgae advances, these innovations form a system that’s being called the ‘circular cell culture system’5. The immediate goal is to have a 30-square-metre closed system that produces one kilogram of cultured meat per day by 2030.

The researchers have been building on their initial findings as one of nine government-funded projects focussed on making food systems more sustainable. Shimizu’s team is part of a national Space Development Utilization Acceleration Program, known as the ‘Stardust Program’. They are working to see if circular cell culture systems might one day supply food for long-term stays on the surface of the moon.

This project is part of Goal 5 of the Japanese government’s National Agricultural and Food Research Organization Moonshot Program, designed to pursue disruptive innovations in Japan and promote challenging R&D.

References

  1. Okamoto, Y. et al. Biotechnol. Prog. 36, e2941 (2020).

    Article  PubMed  Google Scholar 

  2. Haraguchi, Y. & Shimizu, T. Arch. Microbiol. 203, 5525–5532 (2021).

    Article  PubMed  Google Scholar 

  3. Kato, Y. et al. Sci. Rep. 13, 7249 (2023).

    Article  PubMed  Google Scholar 

  4. Haraguchi, Y. et al. Arch. Microbiol. 205, 266 (2023).

    Article  PubMed  Google Scholar 

  5. Haraguchi, Y. et al. Arch. Microbiol. 204, 615 (2022).

    Article  PubMed  Google Scholar 

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