Seminar | Dark energy ecosystem predicted and not predicted by chemical disequilibrium

Dec 11 2018 02:30 PM - Dec 11 2018 04:00 PM

Ken Takai, Ph. D

Japan Agency for Marine-Earth Science and Technology




Over the past 35 years, researchers have explored seafloor deep-sea hydrothermal vent environments around the globe and studied a number of microbial ecosystems there, which is now called as Dark Energy Ecosystems. Bioinformatics and interdisciplinary geochemistry-microbiology approaches have provided new ideas on the diversity and community composition of microbial life living in deep-sea vents. In particular, recent investigations have revealed that the community structure and productivity of chemolithotrophic microbial communities in the deep-sea hydrothermal environments are controlled primarily by variations in the geochemical composition of hydrothermal fluids.

This was originally predicted by a thermodynamic calculation of energy yield potential of various chemolithotrophic metabolisms in a simulated hydrothermal mixing zone. The prediction, called as McCollom and Shock's prediction,  has been finally justified by the relatively quantitative geomicrobiological characterizations in various deep-sea hydrothermal vent environments all over the world. Thus, there should be a possible principle that the thermodynamic estimation of chemolithotrophic energy yield potentials could predict the realistic chemolithotrophic living community in any of the deep-sea hydrothermal vent environments in this planet. Once such a principle is realized, the principle can be applied not only to exploration of extant dark energy ecosystem but also to understanding of the most ancient dark energy ecosystem in the Earth and even the likely extraterrestrial dark energy ecosystems in our solar system.

In addition, recent electrochemical studies of deep-sea hydrothermal mineral deposits and environments have pointed to the existence of microbial ecosystem beyond McCollom and Shock's prediction.