Perth Laboratory – Public Seminar Series 2009

The Prokaryotes and their activities and habitats in sub-seafloor sediments

Professor R. John Parkes
School of Earth and Ocean Science
Cardiff University, UK

*Tuesday 7 July 2009 at 3.30pm, CSIRO Auditorium

Abstract

Deep marine sediments were once thought to be devoid of life. Geomicrobiological analyses by the Ocean Drilling and Integrated Ocean Drilling Programs (ODP, IODP) has changed this perception. Remarkably, sizeable populations remain present in sediments >1 km deep. Bacteria and Archaea can colonize sediments down to basement rock, where activity can be stimulated by basement fluids, challenging claims from geochemical modelling that most sub-seafloor microorganisms are inactive or adapted for low metabolic activity.

In deep sediments, microbial cell numbers reflect the preferential utilization of labile organics. As temperatures increase, reactivity of recalcitrant organic matter may increase, leading to a low continuing energy supply. In deeper layers and at higher temperatures, direct formation of thermogenic compounds can fuel the base of the deep biosphere.

We have yet to reach the extreme limit of the sub-seafloor biosphere, and this might extend the known limits of life, the implications for the origin of life on Earth, and the possible existence of deep biospheres on other planets.

About the speaker

Professor John Parkes joined the School of Earth Ocean Sciences in June 2003 to set up a new Geomicrobiology Research Group under the Cardiff University Research Magnet Initiative.

Formally from Bristol University, Professor Parkes is currently head of Geomicrobiology and a Distinguished Research Professor at Cardiff University. He has a B.Ed (Hons) from Birmingham University and PhD from Aberdeen University. He is a member of the Society for General Microbiology and International Committee Member of the ISEB (International Symposium on Environmental Biogeochemistry).

Professor Parkes has played a major role in Geomicrobiological Research, in particular, in establishing the presence of the sub-seafloor biosphere, possibly the largest prokaryotic habitat on Earth.

This seminar was made possible through the support of the Australia New Zealand Integrated Ocean Drilling Program Consortium (ANZIC).

*Note: this seminar is scheduled for Tuesday instead of the usual Thursday

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