In a recent study published Nov. 19 within the News, scientists have used the gene-editing tool CRISPR to enhance how efficiently a fungus produces proteins while also reducing the environmental footprint of that production by 61 percent—all without introducing foreign DNA. The modified fungus has a meatier flavor and is less complicated for people to digest than the natural strain from which it was produced.
“There is a popular demand for better and more sustainable protein for food,” says corresponding writer Zhao Liu of Jiangnan University in Wuxi, China. “We successfully made a fungus not only more nutritious, but also more environmentally friendly by tweaking its genes.”
The need for sustainable proteins and alternatives
Animal agriculture accounts for about 14% of world greenhouse gas emissions. It also requires large amounts of land and fresh water, each of that are increasingly under pressure attributable to climate change and human activity. Because of those challenges, microbial proteins present in yeast and fungi have gained attention as a promising alternative to meat.
Of the numerous mycoprotein sources to this point, the fungus Fusarium venantum has develop into a distinguished selection because its natural flavor and texture closely mimic meat. It has already been approved to be used in several regions, including the UK, China and the US.
Why is improvement needed?
Even with its advantages, Fusarium venatum has thick cell partitions that limit how well humans can digest it. Its preparation can also be resource intensive. Even modest amounts of mycoprotein require significant input, and spores should be cultivated in large metal tanks crammed with sugar-rich feedstock and added nutrients akin to ammonium sulfate.
Liu and his colleagues wanted to find out whether CRISPR could make the fungus easier to digest and still make it more efficient to grow while avoiding the introduction of foreign DNA into the organism.
Modification of key genes that promote performance
To explore this approach, the researchers removed two genes linked to the enzymes chitin synthase and pyruvate decarboxylase. Removal of the chitin synthase gene resulted in a thinner cell wall, making internal proteins more accessible for digestion. Deletion of the pyruvate decarboxylase gene fine-tuned the fungus’s metabolism, reducing the quantity of nutrients needed for protein production.
Their evaluation revealed that the modified strain, named FCPD, used 44% less sugar to make the identical amount of protein as the unique strain and did so 88% faster.
“Many people believed that mycoprotein supplementation was more sustainable, but no one had really considered how to reduce the environmental impact of the entire production process, especially when compared to other alternative protein products,” says first writer Xiaohui Wu of Jiangnan University.
Life cycle footprint and global comparison
The team then assessed the environmental footprint of FCPD throughout its life cycle, from laboratory spores to products akin to inert meat on an industrial scale. They modeled production in six countries with different energy systems, including Finland, which relies heavily on renewable energy, and China, which relies heavily on coal. In each scenario, FCPD produced lower environmental impacts than conventional. Over its entire life cycle, FCPD production reduces greenhouse gas emissions by 60%.
How does FCPD compare to animal protein?
The researchers also compared the results of FCPD production to those related to raising animals for food. Compared to poultry production in China, FCPD requires 70% less land and reduces the potential for freshwater pollution by 78%.
“Such gene-modified foods can meet growing food demands without the environmental costs of conventional farming,” Liu says.
This work was supported by the Key Research and Development Program of China, Jiangsu Basic Research Center for Synthetic Biology, the Natural Science Foundation of Jiangsu Province, and the Postgraduate Research and Practice Innovation Program of Jiangsu Province.