2022 Benjamin Franklin Medal in Earth and Environmental Science presented to Sallie W. Chisholm, Ph.D.

Abstract

Sallie W. Chisholm was instrumental in discovering the marine phytoplankton Prochlorococcus, the most abundant photosynthesizing organism on Earth. Chisholm and her collaborators’ discovery ini- tiated a major breakthrough for understanding the photosynthetic processes in the world oceans and their relevance to Earth’s climate. Chisholm has made key contributions to some of the most insightful and influentia scientifi studies published in the past 40 years, and her research has revolutionized our views of the importance of tiny cells known as Prochlorococcus . Chisholm’s study of Prochlorococcus as a model organism and her pioneering use of genetic tools have provided critical insights into ge- netic diversity, adaptation, and the role that viruses play in evolution. Chisholm and her collaborators’ discoveries of the vital role that Prochlorococcus plays in the ocean carbon cycle have fundamentally changed how we understand the functioning of ocean microbial community structure, the ocean carbon cycle, and marine ecosystems, with important policy implications for climate change.