Then the team added a second microorganism, Corynebacterium glutamicum, which feeds on those nitrogen sources and produces lysine. Lysine is one of the nine essential amino acids that humans must obtain through their diet.

The partial breakdown of proteins brings a second benefit: it makes plant proteins easier to digest. That matters because many crops contain antinutrients — compounds that interfere with the body's ability to absorb nutrients from plant-based foods.

"The interesting thing is that we can use microorganisms to improve the amino acid profile of plant-based ingredients while also making plant proteins easier to digest by partially breaking them down," Solem explains. The group has demonstrated the principle with lysine and expects to have solutions ready soon for two additional essential amino acids.

Feed first, food next

The results come out of the NextOrganic project, which focuses on animal feed, but the researchers say the same technology can improve plant-based foods for human consumption. They mainly worked with faba beans and rapeseed press cake — the protein-rich material left after oil is pressed from rapeseed — because both crops are produced in large volumes in Denmark and the rest of Northern Europe. Both can replace imported soy in animal feed, and the technology has also proven effective with other crops.

The approach could help in pig and poultry farming. When feed lacks essential amino acids, animals grow more slowly and get sick more easily. Farmers typically respond by overfeeding protein or adding fermentation-produced amino acids to the ration.

"In organic pig and poultry production, it is not permitted to add synthetic amino acids to the feed, so overfeeding with protein is the only option. If the animals are given more protein than they can utilize, they excrete more nitrogen via urine and feces, which places a strain on the environment," says Jan Værum Nørgaard, professor at the Department of Animal and Veterinary Sciences at Aarhus University.

Improving the protein composition of feed could therefore cut both feed waste and nitrogen pollution.

Broader prospects, with caveats

The researchers believe the method could eventually help alleviate malnutrition in low-income countries, where diets heavily based on plants sometimes fail to deliver enough essential amino acids. In practice, the technique could extract greater nutritional value from the same quantity of plant-based food or feed.

For now, the published work covers only lysine enrichment in specific crops, and solutions for other essential amino acids are still in development. How the fermented ingredients perform in large-scale feed and food production remains to be tested. Still, the study demonstrates a simple, adaptable fermentation route to a problem that has long limited the value of plant protein — for livestock and for people alike.