//
you're reading...

Microbiology

A blanket of oil: the role of bacteria in cleaning up after Deepwater Horizon

 

Handley KM, Piceno YM, Hu P, Tom LM, Mason OU, Andersen GL, Jansson JK, Gilbert JA. 2017. Metabolic and spatio-taxonomic response of uncultivated seafloor bacteria following the Deepwater Horizon oil spill. ISME Journal 11:2569-83. doi:10.1038/ismej.2017.110

 

The impacts of the Deepwater Horizon oil spill didn’t end with the capping of the Macondo well in 2010. While ships were able to use booms to trap and collect oil that slicked on the Gulf of Mexico’s surface, nearly a quarter of the spilled oil – about one million barrels’ worth – remained deep in the water column more than 3,000 feet below the surface. That oil didn’t just disappear. It drifted in a plume as far as 35 miles from the well site, slowly sinking towards the seafloor. The question for scientists was, what would happen to it after it settled there?

 

The answer to that question depended entirely on how microorganisms living in the seafloor would respond to being covered in a layer of oil. In every handful of seafloor mud, hundreds of millions of bacteria and related microorganisms make a living by eating detritus – the remains of dead fish and algae – that rains down onto the seafloor. But oil is vastly different than detritus to a bacteria’s stomach, and it remained unclear what types of bacteria, if any, could eat away at the blanket of oil.

Map of the extent of the surface oil spill following the Deepwater Horizon. Image courtesy of NOAA.

To find out, Kim Handley and colleagues sailed out to the Deepwater Horizon site only two months after the well had been capped. By this time, other researchers working to trace the sinking plume of oil had confirmed the swath of seafloor that had been coated in oil so that Handley was able to target areas of both high and low oil contamination. The team used a device known as a mega corer to collect sediments, which lands on the seafloor gently enough to leave the surface relatively undisturbed, but with enough force to collect mud into the core barrel.

 

Back on shore, the team went to the lab to extract all of the DNA from the thousands of different species of microorganisms living in the mud they collected and then sequenced it. The result was a tangle of millions of gene sequences – some of which encoded proteins that played a role in oil degradation, but most of which were simply genes that every bacteria species shares. The goal, however, was to find out which species those oil degradation genes came from. So the researchers took that tangle of sequences and tried to piece them together one-by-one by finding areas where the DNA sequences of two snippets overlapped – an impossible task by hand, but something that recent advances in computational biology have made readily possible.

 

Using this approach, Handley’s team was able to recover 57 distinct genomes belonging to bacteria that have the genes necessary to consume oil – a huge number of completed puzzles from the original pile of millions of DNA pieces. This analysis first of all pointed to the identities of these bacteria and clearly showed that they came from several different types of bacteria that are about as evolutionarily related as humans and fish.

Satellite image of the surface oil plume. Nearly one-quarter of the oil spilled from the Deepwater Horizon remained deep in the water column before sinking onto the seafloor. Image courtesy of NASA.

But even more important, examining the sites close to and far from the Deepwater Horizon well site revealed that almost all of these different bacteria were present everywhere the team sampled – including sites that saw very little oil contamination. That means that these oil-consuming bacteria likely didn’t spring up overnight with the appearance of oil or get transported across the Gulf of Mexico by the oil plume itself, but rather that they are native to the seafloor mud across the Gulf.

 

That makes sense given that simple hydrocarbons with some similarities to oil, like methane and butane, are found throughout the Gulf of Mexico seeping naturally out of the seafloor. However, this finding also has important implications for how we think about the role of microorganisms in cleaning up after oil spills. The microbial response to oil settling onto the seafloor in the Gulf of Mexico depended on microorganisms that were native because of the Gulf’s already frequent exposure to hydrocarbons. But if oil were spilled in an area where these bacteria are not present, for example in the case of an oil tanker spill, microorganisms in the seafloor may not be able to consume the oil.

 

While the Deepwater Horizon spill was an environmental catastrophe, it did provide scientists with a natural laboratory to learn more about how microorganisms respond to oil spills on the seafloor. And while in an ideal world another spill would never happen, the results of Handley and her team are a starting point for understanding whether we can count on bacteria to clean up the seafloor in the event of a spill.

 

Discussion

No comments yet.

Post a Comment

Instagram

  • by oceanbites 2 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 3 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 4 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 5 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 7 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 8 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 8 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 9 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 9 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 10 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 11 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 11 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com