Bio-Trap® Samplers Facilitate Great Strides Toward Gulf Oil Spill Clean-up
On April 20, 2011, the Deepwater Horizon Mobile Offshore Drilling Unit exploded 50 miles off the coast of Louisiana, spilling over four million barrels of oil into the Gulf of Mexico. Although the impact on the environment has been catastrophic, the spill has allowed scientists a better understanding of how petroleum pollutants behave in deep-sea waters. One team of researchers led by Terry Hazen of Lawrence Berkeley National Laboratory is studying the microbial communities that feed on hydrocarbon components of oil. By using unique sampling tools called Bio-Traps®, Hazen has been able to gather a great deal of information about how these microorganisms degrade oil.

The Bio-Trap®, developed by Microbial Insights of Rockford, Tennessee, is a sampling device that was baited to attract the oil eating microorganisms. It is often difficult to duplicate in-situ conditions in the laboratory and the results often do not correlate to the field. Benefiting from the fact that microbes prefer to be attached to a surface rather than free floating, Bio-Traps® provide a substrate where microorganisms can form a biofilm, a naturally forming aggregate.

The Bio-Trap® has a unique sampling matrix composed of Bio-Sep® beads. The beads are 2-4 mm in diameter and are an engineered composite of Nomex® and powdered activated carbon (PAC). When a Bio-Trap® sampler is placed in an environment where pollutants are present, the Bio-Sep® beads absorb contaminants and nutrients, essentially becoming an in-situ microcosm with an incredibly large surface area (~600 m2/g). The collection of microorganisms in this state provides information that is more indicative of the natural microbial ecology than in other sampling methods.

Hazen’s team suspended the baited Bio-Traps® riser from the well head to the recovery vessel placing them at various levels over the damaged well. After a week, the Bio-Traps® were gathered, frozen, and sent to the lab for analysis. Hazen’s study revealed that oil-eating microbes that normally thrive on the oil that leaks from natural seeps in the area, had greatly amplified in number in the contaminated waters. He found sixteen groups of hydrocarbon-loving bacteria that were enriched within the plume that developed in the deep water, as a result of the Gulf’s current. These bacteria were able to digest the hydrocarbons in oil in the chilly 5 degree Celsius environment that would impede most microorganisms. The plume was broken up much more quickly than anticipated due to the increased number of these degrading bacteria.

The Bio-Trap® sampler, facilitated analysis of the RNA, DNA, proteins, and lipids of the bacteria from the site and determined their community structure in this deep-sea plume, compared to those outside of the plume. He was able to isolate over 1,600 genes involved in breaking down oil, many of which were much more active in the bacteria within the plume. The results suggest that the deep ocean has its own cleanup crew that is standing by to help eliminate oil contamination. These bacteria have developed over millennia, evolving to tolerate the frigid temperature at the depths where the plume exists.

Hazen and his team were able to determine what happens to the oil over time at varying depths as a function of the microbial communities dining at the Bio-Traps®. The data obtained from their study has provided many new insights into more efficient remediation in the case of any future accidents or petroleum leaks.