A new study in the journal Nature suggests that moving away from animal meat consumption and toward meat substitutes produced from fermenting microbes could powerfully alleviate deforestation and other planet-warming environmental harm. The modeling study found that replacing 20 percent of global consumption of beef and other grazing livestock with microbial proteins grown from fungus could cut annual deforestation in half by 2050, while also lowering greenhouse gas emissions. These gains would lessen, however, with even more alternate meat, the study found.
“The production of ruminant meat has a very negative environmental footprint,” said Florian Humpenöder, the lead author and a sustainability scientist at the Potsdam Institute for Climate Impact Research in Germany. “Part of the solution to this problem could be existing biotechnology. And this is where the microbial protein comes in.”
Humpenöder said the scale of the benefits indicated by his team’s models surprised him. Replacing meat from livestock with these types of proteins show “you would need much less agriculture land, and it would avoid quite a sizable chunk of deforestation.”
The paper also predicted that as humans removed even more grazing livestock out of the human diet, the gains in deforestation loss would slow. In one scenario where 50 percent of meat-eating was replaced by microbial protein, the deforestation loss slowed.
“There is a nonlinear effect,” Humpenöder said. “For deforestation and the related CO2 emissions, they mostly depend on how agricultural production is changing. They do not depend so much on the level of production but more on how it’s changing.”
“If you further increase the replacement [with microbial proteins], we actually see a decreasing ruminant meat demand, reducing the overall pressure on the system,” he added. “It’s also explaining why this land-saving effect is somewhat diminishing.”
There are several types of meat substitutes on the market, including plant-based products such as soybean burgers, as well as meat cells grown in cultures. The Nature study focused on a third category: proteins that are derived from microbes and fermented in tanks called bioreactors. Also known as mycoproteins or single-cell proteins, they tend to be grown in a liquid feedstock — a sugar water with other nutrients and minerals — requiring far less land and water than cattle grazing.
The technology to produce a biomass with a meat-like texture by relying on fermentation dates back decades but has flourished in recent years amid the growing interest in substitutes for meat. There are nearly 100 companies involved in creating such alternative proteins operating in more than two dozen countries, according to a 2021 report on the fermentation industry from the Good Food Institute.
Some of these are well-known brands that have operated for years, such as the Britain-based Quorn, which produces a range of meatless patties, nuggets and fillets. Others are newer, such as Colorado-based Meati Foods, which makes whole steaks and cutlets grown from mycelium.
The alternative protein market is still emerging. It accounts for about 1.5 percent of total meat consumption in the United States, and microbial proteins are just a small fraction of that, according to Liz Specht, vice president of science and technology at the Good Food Institute.
There are obstacles beyond consumer tastes, such as how much steel fermenting equipment is available. But the industry has been growing rapidly, Specht said.
“A lot of companies are looking at this growing consumer interest in plant-based meat alternatives and recognizing that we just barely scratched the surface of what’s possible for microbial proteins to be part of that solution landscape,” she said. “Now there’s been an explosion of new companies leveraging microbial fermentation.”
Some of that is companies focusing on making the protein biomass — the substitute meat itself — while other are using microbial cells as hosts for specific ingredients: milk proteins, egg proteins or proteins that contribute to the flavor of meat substitutes.
Specht called the Nature study “exciting” because it focused on the industry’s “displacement effect” — not just looking at the environmental impact of these alternative meats but how they might take other harmful industries out of the picture.
“We’re not just producing more microbial protein in a vacuum,” she said. “The intent here is that this is displacing demand for conventional animal proteins, particularly ruminant meat, as the most egregious land use offenders.”
The model that Humpenöder and his team used to estimate how using meat substitutes might impact deforestation was unique, he said, because it didn’t rely on life cycle assessments, a way to compare the environmental impact of different products.
“These factors are static because they cannot account for future systematic changes, like changes in population, changes in dietary patterns, in income, in technology, in food demand,” he said. “Therefore these factors cannot be used to scale up the impact of microbial proteins within the context of the whole food and agricultural system. This is exactly the novelty of our study.”
The paper predicted that on the current trajectory, global forest loss would be driven in coming decades largely by converting forests to pastures for animal grazing in sub-Saharan Africa and Latin America. But they found that if 20 percent of protein consumption per capita from meat was replaced by microbial protein by 2050, the reduced demand for animal feed would offset clearing new pasture. They predicted 56 percent less deforestation and 56 percent less net carbon-dioxide emissions from land-use change.
Humpenöder said that ultimately he considers microbial proteins just one of many potential ways to fight the climate crisis and the destruction of the natural world.
“It should not be seen as a silver bullet solution to the whole climate and biodiversity crisis,” he said. “It should more be seen as part of a portfolio of options to address climate change and biodiversity loss.”
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