Figure. 2 (IMAGE) Tokyo Institute of Technology Caption Sulfide is formed by microbes which use sulfate in their energy metabolism, and this can be trapped for billions of years in iron sulfide minerals like those of the FeS2 mineral pyrite in the photo. New research by Sim and colleagues shows the importance of an individual cellular enzyme in controlling the final mixture of sulfur isotopes in these minerals, in turn linking biochemistry, cell physiology, and the record of life on planet Earth. Credit Photo credit: Yuichiro Ueno, ELSI Usage Restrictions The image may only be used with appropriate caption or credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.