In this very short video - Genetically Engineering Pigs to Reduce Environmental Pollution - I look at how genetically engineering a pig has produced an animal that is less harmful to the environment.
The problem of phosphate pollution in the runoff from farms, particularly in pig farming, is a significant environmental concern. Animals' diets are often rich in grains, which contain phytic acid, a compound that pigs cannot digest due to the absence of a specific enzyme. The undigested phosphate-rich phytic acid is then excreted as waste, contributing to environmental issues like algal blooms and water contamination.
Phytic acid, found abundantly in grains, is a form of phosphorus that pigs—and many other animals—cannot utilise because they lack the phytase enzyme to break it down. Without this enzyme, the phosphorus passes through the pigs' digestive system and is excreted, leading to the concentration of phosphate in the environment.
To combat this issue, pigs have been engineered to contain the E. coli appA gene, which enables them to produce phytase, the enzyme needed to digest phytic acid. This modification allows the pigs to break down the phytic acid in their diet, effectively reducing the amount of phosphate in their waste.
What makes this solution particularly innovative is the way the gene is expressed. The E. coli appA gene is under a promoter from a mouse, which regulates the expression of proteins in the mouse salivary gland. This means that the pig only produces the phytase enzyme in its saliva. This targeted expression ensures that the enzyme is active exactly where it needs to be—in the pig's mouth. As the pig chews and swallows, the phytase is mixed with the grain, breaking down the phytic acid before it can pass through the digestive system.
This genetic modification significantly lowers the levels of phosphate pollution associated with pig farming by reducing the amount of undigested phytic acid excreted by pigs.
