Lettuce Engineered to Produce 'Meaty' Protein Myoglobin

British researchers have developed a method to produce myoglobin, the protein responsible for the characteristic red color and flavor of meat, in genetically engineered lettuce. This breakthrough, published in 'Frontiers in Plant Science,' could offer a new avenue for producing plant-based meat alternatives.

The research team, from Imperial College London and the Bezos Center for Sustainable Protein, inserted genes for pig myoglobin into the chloroplasts of tobacco and lettuce. They successfully synthesized myoglobin in these plants, marking the first time an animal protein has been stably expressed and passed down through generations in plant chloroplasts. The chloroplasts were chosen for their higher protein production efficiency compared to the cell nucleus.

While the myoglobin yield in the engineered tobacco and lettuce was about 800-810 mg per kg of dry weight, it remains significantly lower than in actual meat. Furthermore, only about 35% of the purified myoglobin from tobacco contained the iron-containing heme molecule, which is crucial for meat's color and taste. The researchers suspect a bottleneck in the plant's heme production pathway.

Despite these challenges, the researchers highlight the potential for this technology. They note that plant cultivation requires minimal resources, suggesting that protein production per area could eventually rival that of the livestock industry, while significantly reducing water usage and greenhouse gas emissions. This method also bypasses the need for large-scale fermentation facilities used in current plant-based protein production, allowing for cultivation in open fields or greenhouses. The myoglobin produced could be used as an ingredient in alternative meats or even as a standalone fortified food product.