Engineered oilseed produces fat molecules for formula milk

A team from the UK’s Rothamsted Research Centre has genetically engineered a cousin of the mustard oilseed plant to produce fat molecules resembling those in human breast milk.

“The infant formula market is currently estimated to use nearly half a million tonnes of vegetable-derived fat per year,” the scientists wrote in their study, published last month in the Proceedings of the National Academy of Sciences of the USA (PNAS).

“While some milk formulas already contain triacylglycerol that mimics the structure of human milk fat, these human milk fat substitutes (HMFS) are expensive to make, while the process generates solvent waste and uses palm oil – the growing of which has been blamed for tropical deforestation,” the centre said in a press release. Costs were one of the main reasons why HMFS was only found in about 10% of infant formulas and the centre said it hoped the team’s breakthrough could lead to improvement in all grades of formula for babies who needed it.

The scientists tested their method on an oilseed plant called Arabidopsis thaliana oilseed plant, a cousin of the mustard plant.

“In human milk fat, saturated fatty acids are esterified to the middle position on the glycerol backbone giving the triacylglycerol molecules an unusual stereochemistry that assists nutrient absorption in the infant gut,” the scientists wrote in the PNAS.

The team modified the genes responsible for a metabolic pathway in Arabidopsis thaliana. They relocated an enzyme, lysophosphatidic acid acyltransferase (LPAT), from where it usually resides within the cell’s light-capturing chloroplasts, to the endoplasmic reticulum, an area of the cell where fats are made. This led to LPAT being incorporated into the fat production pathway, resulting in triacylglycerols with more than 70% of the saturated fatty acid palmitate in the middle position, thereby mimicking the human milk fat stereoisomeric structure.

Lead researcher, Dr Peter Eastmond said several oilseed crops, such as sunflower and rapeseed, could be candidates for HMFS production.

“Translation of our technology might conceivably provide a cheaper and more sustainable source of HMFS for infant formula.”