The production of certain chemicals has already become an important biotechnological industry. Vitamin C is a prime example. Humans, as well as other primates, guinea pigs, the Indian fruit bat, several species of fish, and a number of insects, all lack a key enzyme that is required to convert a sugar, glucose, into vitamin C.
No single bacterial genus or species is known that will carry out all of the reactions needed to synthesize vitamin C, but there are two (Erwinia species and Corynebacterium genus) that, between them, can perform all but one of the required steps. In 1985 a gene from one of these genus (Corynebacterium) was introduced into the second organism (Erwinia herbicola), resulting in a new bacterial form. This engineered organism can be used to produce a precursor to vitamin C that is converted via one chemical reaction into this essential vitamin. The engineering of many other microorganisms is being used to replace complex chemical reactions. For example, amino acids, needed for dietary supplements, are produced on a large scale using genetically modified microorganisms, as are antibiotics.