Olivier Rouxel Jeffrey C. Alt Nobumichi Shimizu Shuhei Ono Rosalind M. Coggon Wayne C. Shanks III Laura Lapham Marcus Elvert Xavier Prieto-Mollar Kai-Uwe Hinrichs Fumio Inagaki Andreas Teske Mark A. Lever 2013 <p><span>Sediment-covered basalt on the flanks of mid-ocean ridges constitutes most of Earth's oceanic crust, but the composition and metabolic function of its microbial ecosystem are largely unknown. By drilling into 3.5-million-year-old subseafloor basalt, we demonstrated the presence of methane- and sulfur-cycling microbes on the eastern flank of the Juan de Fuca Ridge. Depth horizons with functional genes indicative of methane-cycling and sulfate-reducing microorganisms are enriched in solid-phase sulfur and total organic carbon, host δ</span>¹³<span>C- and δ</span>³⁴<span>S-isotopic values with a biological imprint, and show clear signs of microbial activity when incubated in the laboratory. Downcore changes in carbon and sulfur cycling show discrete geochemical intervals with chemoautotrophic δ</span>¹³<span>C signatures locally attenuated by heterotrophic metabolism.</span></p> application/pdf 10.1126/science.1229240 en Science Evidence for microbial carbon and sulfur cycling in deeply buried ridge flank basalt article