Scientists have sought for long to learn more about how the Earth’s oceans absorb carbon dioxide and generally exchange gases with the atmosphere so they can better understand the corresponding effects on climate. To that end, many researchers are turning their attention to the microscopic organisms that help recycle carbon, nitrogen, sulfur and other elements through the oceans. Finding out exactly how and to what degree they do that is an ongoing scientific challenge, and scientists may first have to learn more about how the microbes interact with their environment at the scale of the individual microbe. In recent work, an international team of scientists led by Professor Roman Stocker of the MIT Department of Civil and Environmental Engineering opened a window into that microbial world. The team studied how certain strains of marine microbes find and use sulfur, an element vital to many of this type of microbe. Some microbes ingest the sulfur, convert it and pass it back into the ocean in altered form, keeping the chemical moving through the Earth’s sulfur cycle.