Leo Nicholas Ornston (born 1940) is an American microbiologist who researched the evolution of microbes.
He was a faculty member at Yale University from 1969–2011, where he was made the director of its Center for Biological Transformation.
For graduate school, he attended the University of California, Berkeley in the laboratory of Roger Stanier.
He then did post-doctoral research in Leicester with Hans Kornberg and then at the University of Illinois at Urbana–Champaign with Irwin Gunsalus.
[4] He was also made the director of its Center for Biological Transformation, the goals of which were to understand the fundamental nature of genetic mutation and apply those findings to engineer bacteria that could metabolize toxic pollutants.