Scientists have genetically engineered a close relative of the tobacco plant to pump out nutrients found in human breast milk.
The technology could pave the way for more closely replicating infant formula health benefits of breastfeeding, according to the team behind the work. The study showed that the genetically modified Nicotiana benthamiana can produce complex sugars called human milk oligosaccharides (HMOs) that boost healthy gut bacteria and have benefits for the baby’s immune system.
Dr Patrick Shih, a plant and microbial biologist who led the work at the University of California, Berkeley, said: “Imagine that you could make all the oligosaccharides of human milk in a single plant. Then you could just crushing that plant, extracting all the oligosaccharides at once and adding them directly to infant formula. There will be many challenges in implementation and commercialization, but that’s the big goal we’re trying to move towards.”
Breast milk contains approximately 200 different HMOs, and they are the third most abundant solid component of human milk. They are indigestible for the nursing baby, but serve as food for bacteria that colonize the intestines during the first weeks of life. By promoting healthy gut bacteria, there is evidence that HMOs reduce the risk of viral and bacterial infections and may have other health benefits.
Currently, a small handful of HMOs can be manufactured using engineers E coli bacteria and large producers are begin to incorporate them as an ingredient. But many HMOs remain difficult or impossible to produce this way and isolating the beneficial molecules from other toxic byproducts is an expensive process, so only a limited number of infant formulas include them.
In the latest study, published in the journal Nature Food, the scientists reprogrammed the plants’ sugar-making machinery responsible for linking simple sugars, called monosaccharides, into the vast array of branched chains that make up complex sugars. The scientists inserted genes designed to produce specific enzymes needed to assemble basic sugars into a variety of HMOs. The genetically modified plants produced 11 known HMOs.
“We’ve made three large batches of human milk oligosaccharides,” Shih said. “To my knowledge, no one has ever shown that you can make all three of these groups simultaneously in a single organism.”
It included a compound called LNFP1, which is associated with babies having fewer infections but cannot be made in large quantities using microbial fermentation methods. Shih and colleagues said the approach could lead to healthier and more affordable formula for babies, or more nutritious non-dairy plant milks for adults. Other scientific teams are investigating the potential for HMO-based medicine.
Shih said, “This could enable improved plant-based milks not only for infants, but also for many other facets of adult diet and health. Plants are already designed to produce oils and fatty acids that are better for our health. These are just a few of a growing list of ways we can begin to create designer plants adapted to improve human health.”
