New study shows heat loving bacteria has origins in oil springs and the depths of earth’s crust

Heat-loving bacteria found in the Arctic seabed
have their origins in oil springs and the depths of the Earth’s crust. This is
the finding of a project supported by the Austrian Science Fund FWF, which used
molecular biology to study “misplaced” bacteria such as these. The possibility
that molecular biology could also help track down oil fields gives the project
an interesting economic twist.
They were first
discovered over 50 years ago but their origins have remained a mystery.
Living in the sediment of the Arctic seabed around Spitsbergen are bacteria that
only really thrive in temperatures above 50 degrees Celsius. In fact, the term
“living” can only be applied in the loosest of terms, as the bacteria found here
exhibit little in the way of metabolic activity and spend their existence as
dormant spores. But it is their metabolism that is of most interest, since some
of them are “sulphate-reducing microorganisms” (SRMs) and as such are capable of
breaking down organic material in the absence of oxygen and the presence of
sulphate. It is precisely this capability that gave the first indications of
where these microbial migrants could originate from.
“While we would describe conditions in certain parts
of our planet as inhospitable, others feel right at home there. Thermophilic
SRMs love environments where temperatures exceed 50 degrees Celsius and where
there is a distinct lack of oxygen. In conditions such as these, these
microorganisms are able to break down organic material,” explains Project Leader
Dr. Alexander Loy from the Department of Microbial Ecology at the University of
Vienna, adding: “Underwater oil springs and ecosystems deep in the Earth’s crust
offer just such conditions and were our first thought when trying to pin down
the origins of thermophilic SRMs in Arctic sediment.”
To test out this hypothesis, Dr. Loy and his team
first used appropriate molecular biological methods to determine the
relationships of the thermophilic bacteria. This work, which was supported by
the Austrian Science Fund FWF, focused on 16S rRNA, a component of bacterial
“protein factories”. Due to the essential nature of 16S rRNA for all living
beings, it has changed relatively little over the course of evolution. And these
few changes enable scientists to draw conclusions about relationships between
bacteria. If two species have some of these changes in common, it can be assumed
that they are closely related.
The work quickly yielded results and, in September
2009, initial findings from Dr. Loy’s team and data from colleagues at the Max
Planck Institute for Marine Microbiology in Bremen (Germany), and the
Universities of North Carolina (USA) and Aarhus (Denmark) were published in
SCIENCE. Dr. Loy on the results of this “family history” research: “The closest
relatives of the thermophilic bacteria in the Arctic come from oil fields in the
North Sea. Up to 96 percent of the 16S rRNA in these species is identical to
that of the species found in Arctic sediment.” These results provided the first
indications of where the bacteria could come from.
Further evidence came from an analysis of the number
of endospores present in the Arctic seabed, which was conducted by Dr. Loy’s
international colleagues. Based on the numbers detected, it has been calculated
that 100 million bacterial spores are deposited for each square metre, each
year. This was the second key indication of the origin of these bacteria. It is
evident that a big enough population must exist to ensure a continuous supply.
Only oil fields and ecosystems in the Earth’s crust, where high temperatures
provide ideal conditions for heat-loving bacteria, could be responsible for such
If the thermophilic SRMs in Arctic waters do
originate from underwater oil springs, the methods used could also have
applications in oil exploration. Although this particular aspect was not a focal
point of Dr. Loy’s FWF project, it could have a very practical side