 Genetic engineering research is actively pursuing bacterial strains to improve the efficiency of production and allow lysine to be made from other substrates.The 1993 film "Jurassic Park" (based on the 1990 Michael Crichton novel of the same name) features dinosaurs that were genetically altered so that they could not produce lysine, an example of engineered auxotrophy.This was known as the "lysine contingency" and was supposed to prevent the cloned dinosaurs from surviving outside the park, forcing them to be dependent on lysine supplements provided by the park's veterinary staff.