Study bacteria eating oil and gas in oil spills

In a new study, a team of scientists led by David Valentine, a geochemist and professor of Earth Science at UC Santa Barbara University, United States and Molly Redmond, a room graduate student. Valentine 's experiment: used DNA to identify the types of bacteria present in the Gulf of Mexico after the Deepwater Horizon oil spill occurred , as well as the bacteria responsible for consuming the amount of gas. naturally released into the environment immediately after the oil spill occurred. Researchers found that water temperature plays an important role in how bacteria respond to oil spills.

The results of this study were published in the Proceedings of the US National Academy of Sciences.

The Deepwater Horizon oil spill is unique, according to scientists, because it occurs at a fairly deep depth and has a lot of natural gas escaping, mainly methane, ethane and propane. In previous studies, Valentine, Redmond and colleagues found that ethane and propane are hydrocarbon compounds mainly consumed by bacteria in June 2010, two months after the incident. In September 2010, scientists found that these gases and all methane gas were consumed by bacteria.

In May and June 2010, scientists discovered that the Deepwater Horizon submerged microbial communities were flooded with bacteria: Oceanospirillales, Colwellia and Cycloclasticus - and the distribution density of the This bacterium is very different in quantity from controlled samples without large concentrations of oil or gas and also from surface oil slicks collected at the same time.

Molly Redmond collects water samples for methane analysis.

"Water is warmer on the surface and colder at depths of about 80 degrees (Fahrenheit) compared to 40 degrees, quite close to the temperature in your refrigerator , " said Redmond, the study's lead author.

"There is very little natural gas in the oil samples on the surface of the water, which suggests that both the temperature and the concentration of natural gas can play an important role in determining the density of bacteria blooming after the occurrence. Microbial samples found in water samples at depths, in May and June, are related to cold-resistant bacteria, cold-tolerant. more at low temperatures is why we keep food in the refrigerator, but cold-loving bacteria actually grow faster at cold temperatures than at room temperature . "

To provide further evidence of the importance of temperature, scientists add oil to water taken from the Gulf of Mexico and incubate at 40 degrees and at room temperature (about 70 degrees), observing the number of bacteria growing. under different temperature conditions. In microbial samples at 40 degrees, Colwellia is most present, but only found in low numbers of Colwellia in room temperature samples, suggesting that these particular bacteria have an advantage in cold water.

"To find bacteria that consume gases: methane, ethane, and propane, we use a technique called stable isotope exploration: first, we incubate seawater samples from the Gulf of Mexico with isotopes labeled as: methane, ethane, propane , " Redmond said. "The bacteria have grown when they consume methane, ethane, and propane convert the isotope of gas labeled into biomass, including their DNA.

By decoding DNA labeled, we were able to identify bacteria that consumed methane, ethane, and propane; and bacteria consume ethane and propane. For example, we have seen the abundance of Colwellia present in high concentrations in samples collected in May and June, when the consumption of ethane and propane is high, and we keep the oil at temperature is about 40 degrees, but not at room temperature ".

This suggests that the presence of Colwellia bacteria is abundant because they grow well at low temperatures and because they can consume ethane and propane gas, which is rich in oil spills , researchers said. Bacteria that consume methane are a group of bacteria called Methylococcaceae - similar to the bacteria discovered in September after methane has been consumed, suggesting that in fact, Methylococcaceae plays an important role. Important in methane consumption.

"Bacteria 's ability to eat oil also grows in tandem with natural gas, which is an important source of food for them, because these bacteria can only grow in quantity thanks to consumption. Natural gas is abundant, when this gas is consumed, bacteria begin to focus on other components of the oil, " Valentine said . "With this work, we have discovered a number of relationships between hydrocarbon compounds emitted from the incident at the Deepwater Horizon oil rig and the reaction of the bacteria. However, there are still many. Other questions such as how the bacteria interact with each other, and how the oil spill affected the ecosystem. "

This research is supported by the National Science Foundation and the US Department of Energy.