Presentation #413.01 in the session “Titan”. Cross-listed as presentation #106.06.
Saturn’s largest moon, Titan, satisfies three key criteria for life: presence of liquid water, nutrient availability, and energy sources. Furthermore, Titan hosts a massive inventory of simple and complex organic molecules. Acetylene (C2H2) is the main solid photochemical product generated in Titan’s atmosphere and is ultimately deposited onto the surface. With an acetylene-rich surface and other basic requirements for life, Titan is a high-value astrobiology target. On Earth, acetylene frequently inhibits common metabolisms such as nitrogen fixation and methanogenesis. However, acetylene fermenters, or acetylenotrophs, utilize acetylene as the carbon and energy source and are found within several bacterial phyla. Yet despite membership in microbial communities around the globe and under a variety of conditions (e.g. subsurface, ocean sediments, bioremediation sites), acetylenotrophy is an understudied metabolism on Earth. Therefore, we begin our exploration of acetylenotroph habitability on Titan by calculating the Gibbs energy for its catabolic reaction. We present conditions on Titan (pH, temperature, and acetylene concentration) where acetylenotrophy would be energy-yielding.