Do Microbe-Mineral Interactions Produce "Biosignatures"?
When: April 4, 2017 3PM PDT
On Earth, atmospheric oxygen played a significant role in the evolution of complex life. Oxygen levels in the atmosphere are controlled over geological time scales by the burial of iron sulfide minerals and organic carbon in sediments. Microorganisms drive the redox transformations of Fe, S and C from the surface of the Earth down to the depths of the continental and oceanic crusts. Due to their metabolic capabilities, as well as to their surface properties, microorganisms can mediate the precipitation – and influence the morphology and composition – of a variety of minerals. For this talk, I will present experimental work demonstrating the role of sulfate-reducing microorganisms in producing iron sulfide minerals with unique physical characteristics and composition. I will then discuss the potential for microbe-iron sulfide mineral interactions to be used as “biosignatures” for the presence of microbial life in ancient anoxic environments on Earth or elsewhere.