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The bacteria that clean the deep blue sea

Interview: Dr Tony Gutierrez…

The bacteria that clean the deep blue sea

The bacteria that clean the deep blue sea

Interview: Dr Tony Gutierrez

 Whether it’s hungry bacteria mopping up oil spills or microbes with unique properties that could be harnessed for biotechnological applications, Dr Tony Gutierrez is trying to understand the microbiology that drives different processes – research that could help to save billions of dollars or prevent a major environmental disaster...

Certain types of bacteria, found everywhere in the ocean, use oil as their main source of food. And if these bacteria did not exist, the surface of the ocean would be covered with a permanent oil slick, because so much oil enters the sea every year, as a result of both natural processes and human activities. However, when there is an oil spill as disastrous as the Deepwater Horizon incident, which occurred in the Gulf of Mexico on April 20, 2010, releasing an estimated 200 million gallons of crude oil over a period of 83 days, even the bacteria struggle to cope.

Oil exploration is now moving further offshore into much deeper waters in search of ever scarcer and more valuable resources. Deepwater Horizon blew up only a year after it had drilled the deepest oil well in history, and as the industry explores at greater depths, the costs of exploration and recovery increase all the time, as do the risks, with BP (which leased the rig) facing penalties that could reach tens of billions of dollars.

But what if we could speed up the removal of oil pollutants in the sea by feeding the ocean with “designer” micro-organisms that have improved oil-degrading capabilities, or by adding fertiliser that could stimulate the rate at which indigenous oil-degrading bacteria eat up the oil? Would that make it easier and cheaper to recover from disaster? 

According to Dr Tony Gutierrez of Heriot-Watt University, we are still a long way away from a working “solution” for oil spills. But his research in recent years has started to uncover new information on the wide range of bacteria which “eat” or degrade oil, and understand the processes involved. Gutierrez was “in the right place, at the right time” when Deepwater Horizon blew up, working at the University of North Carolina in Chapel Hill, USA. The disaster may have been bad news for the oil industry and the environment, but it was also an opportunity for scientists to monitor, analyse and report the effects of a major spill. To understand what happened to the large volume of oil that had entered the Gulf and had not been recovered by BP or government task forces, a detailed microbiological investigation was carried out, which showed that the massive influx of oil into the Gulf had “triggered dramatic microbial community shifts.”  

Scientists investigating the microbial response to the Deepwater Horizon spill also observed a bloom of particular groups of bacteria in sea surface oil slicks and in deep waters (~1,000 – 1,300m depth) of the Gulf of Mexico, where much of the oil had become entrained. Some of the bacteria identified belong to taxonomic bacterial groups comprising members with known  oil-degrading qualities – e.g. Oceanospirillales and Cycloclasticus. However, Gutierrez points out that molecular studies provide an indication of what these  bacteria might be capable of doing, such as the types of carbon sources (e.g. hydrocarbons) that they can use  as a food source. Other techniques are required in order to infer this with greater accuracy. “Identifying which bacteria played a major role in degrading the oil is an important step to understanding the complex nature of the Gulf of Mexico’s response to the spill,” says Gutierrez.

Using classical microbiological methods supported by a sophisticated DNA-based molecular biological technique called stable-isotope probing (DNA-SIP), Gutierrez and colleagues published their results in The ISME Journal in November 20131, which identified a number of bacterial species that contributed directly to degrading the oil in both sea surface oil slicks and in the deep waters of the Gulf. Their results provided incontrovertible evidence, that was hitherto lacking, on the hydrocarbon-degrading abilities of some of the most dominant bacteria that bloomed in response to the massive influx of oil into the Gulf; in turn revealing a “more complete understanding of their role in the fate of the oil.” The oil-degrading bacteria identified included species affiliated to the genera Cycloclasticus, Alteromonas, Pseudoalteromonas, Marinobacter and Halomonas. A few months earlier, Gutierrez and colleagues published a paper in the journal PLOS ONE2, which provided evidence that some of these oil-degrading bacteria had also helped to trigger the formation of large quantities of particulate organic matter (also known as “marine snow”), and additional results are due to be published this year. In addition to the formation of a very large oil plume that formed in the deep waters (~1,000 – 1,300m depth) of the Gulf, the copious quantities of marine snow that were observed floating on the surface of the sea and within the water column near the spill site, within just two weeks of the blow-out, was one of the other defining features of this historic spill.

 Following this initial research and his recent move to Scotland, Gutierrez now focuses on “identifying new species of oil-degrading bacteria and their role in the removal of hydrocarbons from North Atlantic waters, whilst also continuing my work on the Deepwater Horizon oil spill with my colleagues in the United States and Europe.”

Ultimately, this research will not only lead to a greater understanding of the natural remedial processes that unfold in the ocean during oil spills, and enable better planning before drilling starts, but also to improved methods for dealing with oil spills to minimise environmental impact. 

Working in the lab, says Gutierrez, is rarely realistic enough to represent the complex and dynamic conditions found in the field. “During the Deepwater Horizon spill, the Gulf of Mexico was like a massive laboratory experiment – the real McCoy,” says Gutierrez. “This provided us with a unique opportunity to get right in there at the heart of the spill and study the effects that the oil was having upon coastal, offshore and deep water ecosystems in the Gulf, as well as assess its capacity to recover.” 

Gutierrez also points out that the Gulf of Mexico spill was unprecedented with respect to the vast amounts of oil that had gushed out and the depth at which it occurred – approximately 1,500 metres below the surface, where water temperatures are no higher than 5°C and at high pressure.  “It was a major perturbation, and we are still not there in terms of fully understanding its full impact on the Gulf. But one thing it highlighted was the importance for stakeholders such as funding councils, government and industry to invest more into research and technology to develop and optimise oil spill response contingency plans,” says Gutierrez.

Gene sequencing has improved exponentially over the last ten years, says Gutierrez, enabling scientists to sequence thousands to millions of genes at a time, instead of tens or a couple of hundred. For example, new techniques have helped Gutierrez to identify entirely new species of bacteria.  Another target is to study the functions of genes and how they evolved, and this understanding may eventually lead to practical solutions such as methods for dealing with oil spills. We know bacteria eat oil but “chucking bags of fertiliser into the sea” would not necessarily be an efficient response to an oil spill. “There is no single solution in sight,” Gutierrez explains, but new advanced techniques are beginning to shed light on possible future approaches. “We are still only scratching the surface, however,” he adds, “and the more we know, the more questions we ask.”

The Scottish connection

Gutierrez graduated with a PhD in Microbiology & Immunology in 1999 from the University of New South Wales in Sydney, subsequently moving to the University of Florida for post-doctoral research experience. He then returned to Australia for a year before working in Scotland from 2003 to 2008 as a researcher at the Scottish Association for Marine Science (SAMS) in Oban.
He spent the next three years working between the University of North Carolina at Chapel Hill and Lancaster University, before accepting his current position at Heriot-Watt University in Edinburgh in 2012 as Associate Professor of Microbiology, and successfully applying for funding from MASTS (the Marine Alliance for Science and Technology for Scotland). 

As a microbiologist, Gutierrez is a specialist who offers different skills to MASTS, and is also in special demand because of his microbiological and molecular expertise, as well as his recent experience in the Gulf of Mexico and resultant research. His main collaborations until now have been with researchers in Australia, the USA and Europe, including a team in Vienna who are studying the microbiota of the human gut; but now that he is part of MASTS, new possibilities may arise in Scotland.  Gutierrez has already started working with other groups that are a part of MASTS and is also involved in a new Doctoral Training Programme funded by NERC (the Natural Environment Research Council) that was awarded to Heriot-Watt as the lead partner to support over 85 PhD studentships in Oil & Gas research over the next 6–7 years. 

The future of oil exploration

The work done by Gutierrez in the Gulf of Mexico may also have a major influence on future projects in the North Sea, where most oil exploration until now has taken place in waters less than 200 metres deep, as well as in other deep-water regions of the Atlantic.  In the future, companies may seek to drill in water up to 3,000 metres deep.  The rules of the game will be totally different and better methods of bioremediation will need to come into play. 

Apart from trying to stem the worst effects of an oil spill, Gutierrez highlights three areas where microbial research could help in oil exploration:

  1. Establish a “baseline” for the microbiology of the system before drilling and extraction of oil or gas begins, in order to provide a reference for the pre-spill “status quo” of the system.
  2. During exploration, monitor the microbiology of the system and compare this to the baseline established in Stage 1, in order to detect any changes that might be indicative of contamination (e.g. oil leakage).
  3. Develop a site-specific, targeted bioremediation strategy that could be used to enhance the activities of   indigenous communities of oil-degrading bacteria in the event of a spill.

The implications of Gutierrez’s research into oil-eating microbes go far beyond commercial or regulatory considerations, however, and his wider research interests also extend to other pollutants (e.g., microplastics and nanoparticles) and biotechnology.  “Anyone with an interest to understand the natural environment must at some point in their research require to undertake a microbiological investigation, since microbes are quite often at the heart of how most things work in nature,” he explains. “We are using techniques that cross disciplines,” adds Gutierrez, but the major thrust of his research will continue to focus on what’s going on in the sea, and the hungry bacteria feeding on oil.


1 Gutierrez, T., Singleton, D. R., Berry, D., Yang, T., Aitken, M. D.  & Teske, A. 2013. Hydrocarbon-degrading bacteria enriched by the Deepwater Horizon oil spill identified by cultivation and DNA-SIP. The ISME Journal 7, 2091–2104 (November 2013). doi:10.1038/ismej.2013.98
2 Gutierrez, T., Berry, D., Yang, T., Mishamandani, S, McKay, L., Teske, A. & Aitken, M. D.  2013. Role of Bacterial Exopolysaccharides  (EPS) in the Fate of the Oil Released during the Deepwater Horizon Oil Spill. PLoS ONE 8(6): e67717. doi:10.1371/journal.pone.0067717







"The bacteria that clean the deep blue sea". Science Scotland (Issue Fifteen)
Printed from on 06/07/20 11:37:41 AM

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