Natural Resilience

Communities of microbes build relationships to make the modern world less toxic

When an explosion on the Deepwater Horizon drilling platform occurred in 2010, just over 4 million barrels of crude oil were released into the Gulf of Mexico. Hundreds of people and a variety of technologies were quickly deployed to help restore the area. But arguably, the most effective cleaning agent came in the form of naturally occurring, oil-devouring bacteria.

Terry Hazen, UT/ORNL Governor’s Chair for Environmental Biotechnology, is an environmental biologist who specializes in bioremediation. In other words, he examines how bacteria breaks down and detoxifies hazardous materials.

In the wake of the Gulf disaster, Hazen seized the opportunity to advance his research. The result was a paper he co-authored that appeared on the cover of Environmental Microbiology titled “Deep-Sea Bacteria Enriched by Oil and Dispersant from the Deepwater Horizon Spill.” It documented microbial communities and their natural ability to remove spilled oil from the environment.

Terry Hazen

Terry Hazen

“We are trying to look at and understand environmental systems from the molecular level right up through the ecosystem level and everything in between,” Hazen said.

“There’s a lot of hidden information. Ultimately, we want to understand how organisms create a community, as well as the resilience of the community.”

By studying the relationship between these communities, scientists hope to be able to calculate how they will react when pollutants such as hydrocarbons are introduced and, in turn, how that affects the overall ecosystem.

Certain microbes–primarily bacteria and fungi–are known to break down oil into carbon dioxide and water through a process similar to human digestion by harnessing the released energy to sustain themselves. Over millions of years, some bacteria developed the ability to produce enzymes specific to different aspects of the oil-degradation process. Basically, the bacteria have evolved to be picky eaters.

Hazen and his team investigated a group of organisms in the Gulf of Mexico that preferred to feast on alkanes–a saturated hydrocarbon consisting only of hydrogen and carbon atoms that is typically the dominant component in fuels. The team found that after the alkane-eating bacteria finished eating, the community structure changed and other bacteria stepped up to the buffet line.

“Once particular hydrocarbons were degraded, the community switched and organisms that could effectively compete for what was left began to compete for food,” Hazen said. “We saw a natural progression of keystone species in the community as the oil degraded.”

The discovery got Hazen thinking about the pattern of succession and how species composition changes when different hydrocarbons are introduced into the environment. He decided to recreate the Deepwater Horizon conditions in a lab to study transformations within the microbial community and determine which specific members could degrade oil, regardless of whether or not dispersants were used.

“Ultimately, we learned that microbial communities in the Gulf of Mexico have a high potential for degradation of oil and have adapted rapidly to the introduction of hydrocarbons,” Hazen said.

Bacteria attacking a droplet of oil.

Bacteria attacking a droplet of oil.

This knowledge could prove highly beneficial for similar cleanup and restoration efforts in the future. By knowing how microbial communities will behave in specific hydrocarbon-heavy areas, researchers will be better prepared to assist with immediate restoration. It also could potentially save money by curtailing the use of expensive chemical dispersants.

Interestingly, Hazen found that the bacteria do not just incorporate the oil into their bodies; they completely convert it into proteins, carbohydrates, and their DNA structure. The next step is to investigate how the molecular level transformation affects biological processes on the systems level.

“We want to understand how currents and weather affect the overall community,” Hazen said. “That’s why I say we are taking a biological systems approach.”

Understanding how these other factors influence microbial communities will help scientists evaluate how global climate change could alter their hydrocarbon degrading abilities.

As the demand for crude oil increases, the chances of future spills occuring also increase. Because of his work on the Deepwater Horizon spill, Hazen was named lead investigator for a multi-disciplinary, multi-university research team funded by BP to study potential deep sea drilling sites around the world and assess the environmental risks.

“This research will potentially give us some really exciting results,” Hazen said. “All of these sites are quite deep and might have different types of crude oil, which may help us understand the hydrocarbon transformations occurring in the microbial community and how different or similar they are at each site.”

Once scientists understand how the many variables affect microbial communities, they should be able to predict how the microbes will react to the introduction of hydrocarbons in their environment. Will they be as hungry as the ones in the Gulf? Or will the community structure change completely?

Hazen’s previous work on bioremediation technologies has lead to five patents. He recently submitted a proposal for a collaborative strategic environmental research development program that would involve scientists from a variety of disciplines to study the resilience of our natural world.

“Mother Nature has an incredible resiliency to clean herself up after we make a mess,” Hazen said. “I’m worried about the fact that in the Gulf of Mexico, she’s had too many catastrophic events, and how resilient she actually is, but my hope is that this research will help us understand how resilient Mother Nature can be in the future.”

Published online, Quest, April 16, 2013

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