THE DIRECTED ISOLATION OF MUTANTS PRODUCING INCREASED AMOUNTS OF METABOLITES

A method is described whereby mutants having a directed increased yield of a metabolite may readily be isolated. A culture of bacterial cells is exposed to a gradient concentration of an antimetabolite that is inhibitory to the growth of the organism and mutants are isolated which survive because of an increased yield of the metabolite. This increased yield may be several times that formed by the parent culture. Techniques and results for increasing the yields of pyridoxine, nicotinic acid and thiamine are described.