deep subsurface biosphere of Lake Cadagno

This study comprises one of the first comprehensive microbiological and geochemical characterizations of a complete lacustrine sedimentary sequence covering the ~13.5 kyr environmental history of Lake Cadagno, Switzerland. Both past environmental conditions and ongoing microbial activity appear to influence porewater and solid phase chemistry in the sedimentary record. Surprisingly, an oxidizing fluid source hosting obligately aerobic microorganisms was found below the Lake Cadagno sediment sequence, resulting in an inverse redox gradient that and fuels organic matter remineralization in these deeply buried, severely energy-limited sediments.