Life on (well, under) earth
While Mars Phoenix looks for life on Mars, we’ve just found life on earth – but possibly not in the place you might have expected. Researchers have just found bacteria in searing hot sediments over 1.6 kilometres under the Atlantic seafloor off Newfoundland in Canada. The microbes were found in cores of sediment 111 million years old and at temperatures of 60 to 100° Celsius. This discovery doubles the previous record depth of 842 metres for living organisms. So while we wait to find out if there is life 1 metre under the Martian surface, marvel at the life here on Earth.
Extending the Sub-Sea-Floor Biosphere. Science 2008 320: 1046
Sub-sea-floor sediments may contain two-thirds of Earth’s total prokaryotic biomass. However, this has its basis in data extrapolation from ~500-meter to 4-kilometer depths, whereas the deepest documented prokaryotes are from only 842 meters. Here, we provide evidence for low concentrations of living prokaryotic cells in the deepest (1626 meters below the sea floor), oldest (111 million years old), and potentially hottest (~100°C) marine sediments investigated. These Newfoundland margin sediments also have DNA sequences related to thermophilic and/or hyperthermophilic Archaea. These form two unique clusters within Pyrococcus and Thermococcus genera, suggesting unknown, uncultured groups are present in deep, hot, marine sediments (~54° to 100°C). Sequences of anaerobic methane-oxidizing Archaea were also present, suggesting a deep biosphere partly supported by methane. These findings demonstrate that the sub-sea-floor biosphere extends to at least 1600 meters below the sea floor and probably deeper, given an upper temperature limit for prokaryotic life of at least 113°C and increasing thermogenic energy supply with depth.
See also: Abundance and diversity of microbial life in ocean crust. Nature 453: 653-656 (29 May 2008 )
Tags: Bacteria, Biology, Environment, Microbiology, Science
Super, I am really eager to hear a report from this Mars Phoenix expedition, because I really hope to find at least some traces of bacteria.
This research reminds me of the Romanian cave, that is so old, that has preserved the primary life conditions, and the microflora there resembles this microcommunity, found under the Atlantic ocean and it seems that the biosphere should be reconsider for a new definition.