The most used kinds of insulin are actually obtained from animals, as from cowl as from pigs, the human, named semi-sintetic,
and the biosintetic are produced in experimental models in Escherichia coli bacteria. This last ones are produced by recombinant DNA technology (genetic engineering). The difference between human and bovine insulin is just 3 amino-acid; between human and pig insulin is just 1 amino-acid. So, it is necessary the purification procedures, in fact, changes of amino-acids in the isulins made on differents animals to avoid imunological reactions that start the production of anti-body in the human organism. Besides, the author determine the quality of insulin produced by E. coli as better than human and animal obtained, based in its less complexity and cheapest proceeding to be produced. E. coli presents a great vantage, becouse you do not need a big pool of individuals to obtained a great amount of insulin (the production is so fast), these terms permisse not to sacrifice a large amount of animals to produce less than in bacteria production system.