Good News for a Change, Or More Faulty Science? Newly-Discovered Species of Bacteria Claimed to be Breaking Down Oil in Deepwater Plumes in the Gulf

George Washington's picture

Washington’s Blog

A team of scientists published a paper today in the journal Science which provides some hopeful news.

Specifically, a team of scientists have discovered a new species of oil-eating microbes which thrive in the deepwater of the Gulf of Mexico:


The biological effects and expected fate of the vast amount of oil in the Gulf of Mexico from the Deepwater Horizon blowout are unknown due to the depth and magnitude of this event. Here, we report that the dispersed hydrocarbon plume stimulated deep-sea indigenous {gamma}-proteobacteria that are closely related to known petroleum-degraders. Hydrocarbon-degrading genes coincided with the concentration of various oil contaminants. Changes in hydrocarbon composition with distance from the source and incubation experiments with environmental isolates demonstrate faster-than-expected hydrocarbon biodegradation rates at 5°C.

better, the scientists believe that this new species (pronounced
"gamma-proteo-bacteria") may not suck up as much oxygen as
previously-discovered species:

Based on these results, the potential exists for intrinsic bioremediation of the oil plume in the deep-water column without substantial oxygen drawdown.

This discovery is especially important given that a leading expert on oil-eating microbes - Dr. David Valentine - failed to find any of the leading known oil-eating bacteria in the deepwater plumes.

well-known bacteria - such as Salmonella, Yersinia (plague), Vibrio
(cholera), Pseudomonas aeruginosa (lung infections in hospitalised or
cystic fibrosis patients) and E. coli (food poisoning), as well as a
number of geothermic ocean vent dwellers which eat methane or hydrogen
sulfide - are members
of the Gammaproteobacteria class of microbes. The scientists found a BP
oil-eating species within that broader class of bacteria.

As Lawrence Berkeley Labs - a U.S Department of Energy lab - notes, the new species is closely related to Oceanospirillales, an order within the Gammaproteobacteria class of microbes:

Results in the Science paper are based on the analysis of more than 200 samples collected from 17 deepwater sites between May 25 and June 2, 2010.


The dominant microbe in the oil plume is a new species, closely related to members of Oceanospirillales family, particularly Oleispirea antarctica and Oceaniserpentilla haliotis.


episodic oil leaks from natural seeps in the Gulf seabed may have led
to adaptations over long periods of time by the deep-sea microbial
community that speed up hydrocarbon degradation rates.


One of the
concerns raised about microbial degradation of the oil in a deepwater
plume is that the microbes would also be consuming large portions of
oxygen in the plume, creating so-called “dead-zones” in the water
column where life cannot be sustained. In their study, the Berkeley Lab
researchers found that oxygen saturation outside the plume was
67-percent while within the plume it was 59-percent.

However, as Science News points out, not all experts agree with the new report:

team reports data from late May to early June showing that those
deep-sea plumes enticed a hitherto unknown cold-water–adapted bacterium
to rapidly chow down on the oil.


Indeed, [lead author Dr. Terry
Hazen, co-director of the Earth Sciences Division of the Lawrence
Berkeley National Laboratories] says, those bugs have been so voracious
that for one plume of oil his team had been following, “within the last
three weeks we no longer detect a deep plume. At all.” It went away
approximately two weeks after the well was capped on July 15, he
observes. Its oil “is completely undetectable.”


Also, the
unusual population of oil-digesting bacteria that had inhabited that
plume — and that would ordinarily be expected to stay with it as it
moved — remained behind in a vestigial microbial cloud. “Doesn’t that
suggest biodegradation?” he asks.


Speaking of deep-sea
plumes, “I’ve heard rumors they might have gone missing,” notes David
Valentine, a microbial geochemist at the University of California,
Santa Barbara — but currents might simply have moved them into hiding.
It would be nice to think the oil has been removed, he says. “But if it
sounds too good to be true,” he cautions, “it probably is.” And yes, “This sounds too good to be true.”




Hazen’s interpretation has its skeptics. “Most
of the science associated with this spill has been oversimplified,”
says John Kessler, a chemical oceanographer at Texas A&M University
in College Station
. In a good-faith effort to make sense of
what’s going on, many researchers look to offer interpretations based
on too few data, he charges.


For instance, he says, “what
Hazen was measuring was a component of the entire hydrocarbon matrix,”
which is a complex mix of literally thousands of different molecules.
Although the few molecules described in the new paper in Science may well have degraded within weeks, Kessler says, “there are others that have much longer half-lives — on the order of years, sometimes even decades.”


he points out, many of the tools traditionally used to gauge
biodegradation don’t work well in the field. A few teams have lately
begun transitioning to use of more sensitive probes, he says.


data from those more sensitive tools are fueling his skepticism of
Hazen’s report that microbes have been erasing deep-sea plumes. As
recently as August 22, Kessler says, “I spoke to some of those
researchers out there [in the Gulf], and they told me they were still
seeing plumes

Similarly, as Reuters notes:

to WHOI oceanographer Richard Camilli, the plume could already be
hundreds of miles from its previous location, and Hazen’s team could
simply have missed it. “The plume is not a stationary object,” he told
the Wall Street Journal.


of South Florida microbial ecologist John Paul, part of a recent study
that found oil in Florida fish spawning beds and contradicted federal
claims of the oil’s disappearance, wasn’t convinced by the new results.


differences in bacterial abundance, diversity and hydrocarbon degrading
potential are “slight” between plume samples and regular Gulf seawater,
said Paul.


He also said that the gene-tagging technologies used by
Hazen’s team are used by few researchers “because they are often problematic in execution and interpretation of results.”


According to University of Maryland aquatic toxicologist Carys Mitchelmore, Hazen’s team only measured the breakdown of select compounds in the oil. “There’s lots of other chemicals in the oil,” she said.


She also stressed that it’s
essential to identify what happens when oil is degraded. That catch-all
term implies that it just vanishes, but “sometimes things can be
degraded into more toxic components,”
said Mitchelmore. The latest study did not make those measurements, nor did it test how microbes interacted with chemical oil dispersants used during the disaster.


big take-home is that we don’t know much about many things related to
this spill, the oil fate and its effects” said Mitchelmore. “There are
huge data gaps and uncertainties, conflicting data from many aspects,
and this will continue to happen based on the huge complexity of
studying this.”


“Above all,” said Mitchelmore of the latest study, “note this is all based on 17 sample sites from the field.

As Lawrence Berkeley Labs notes, the research was funded by BP:

... conducted this research under an existing grant he holds with the
Energy Biosciences Institute (EBI) to study microbial enhanced
hydrocarbon recovery. EBI is a partnership led by the University of
California (UC) Berkeley and including Berkeley Lab and the University
of Illinois that is funded by a $500 million, 10-year grant from BP.

Reuters also picks up on the potential conflict of interest:

for the study was provided by the Energy Biosciences Insitute, a joint
project of the University of California, Berkeley, the Lawrence
Berkeley National Laboratory, the University of Chicago at
Illinois-Champaign and BP, who gave the EBI a $500 million, 10-year
grant. Terry Hazen sits on the EBI’s Executive Committee, as does BP executive Tom Campbell. Conflicts of interest are rarely as black-and-white or simple as they seem, but this ought to be mentioned.